diff --git a/Makefile b/Makefile
index 028641b..e190e97 100644
--- a/Makefile
+++ b/Makefile
@@ -17,6 +17,10 @@ RELEASE=$(filter-out scripts/archive.py docs/%.adoc,$(shell git ls-files docs sc
 CXXFLAGS=-g -Wall -Wextra -Werror -pedantic -Wundef -Wshadow -Wcast-align -Wcast-qual -Wold-style-cast -Wdouble-promotion
 LDFLAGS=
 
+ifneq ($(cxxstd),c++98)
+	CXXFLAGS+=-Wzero-as-null-pointer-constant
+endif
+
 ifeq ($(config),release)
 	CXXFLAGS+=-O3 -DNDEBUG
 endif
diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index ee8a666..c4f021b 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -282,7 +282,7 @@ PUGI__NS_BEGIN
 		T* release()
 		{
 			T* result = data;
-			data = 0;
+			data = PUGIXML_NULL;
 			return result;
 		}
 	};
@@ -293,7 +293,7 @@ PUGI__NS_BEGIN
 	class compact_hash_table
 	{
 	public:
-		compact_hash_table(): _items(0), _capacity(0), _count(0)
+		compact_hash_table(): _items(PUGIXML_NULL), _capacity(0), _count(0)
 		{
 		}
 
@@ -302,7 +302,7 @@ PUGI__NS_BEGIN
 			if (_items)
 			{
 				xml_memory::deallocate(_items);
-				_items = 0;
+				_items = PUGIXML_NULL;
 				_capacity = 0;
 				_count = 0;
 			}
@@ -310,11 +310,11 @@ PUGI__NS_BEGIN
 
 		void* find(const void* key)
 		{
-			if (_capacity == 0) return 0;
+			if (_capacity == 0) return PUGIXML_NULL;
 
 			item_t* item = get_item(key);
 			assert(item);
-			assert(item->key == key || (item->key == 0 && item->value == 0));
+			assert(item->key == key || (item->key == PUGIXML_NULL && item->value == PUGIXML_NULL));
 
 			return item->value;
 		}
@@ -326,7 +326,7 @@ PUGI__NS_BEGIN
 			item_t* item = get_item(key);
 			assert(item);
 
-			if (item->key == 0)
+			if (item->key == PUGIXML_NULL)
 			{
 				_count++;
 				item->key = key;
@@ -369,7 +369,7 @@ PUGI__NS_BEGIN
 			{
 				item_t& probe_item = _items[bucket];
 
-				if (probe_item.key == key || probe_item.key == 0)
+				if (probe_item.key == key || probe_item.key == PUGIXML_NULL)
 					return &probe_item;
 
 				// hash collision, quadratic probing
@@ -377,7 +377,7 @@ PUGI__NS_BEGIN
 			}
 
 			assert(false && "Hash table is full"); // unreachable
-			return 0;
+			return PUGIXML_NULL;
 		}
 
 		static PUGI__UNSIGNED_OVERFLOW unsigned int hash(const void* key)
@@ -465,16 +465,16 @@ PUGI__NS_BEGIN
 		{
 			xml_memory_page* result = static_cast<xml_memory_page*>(memory);
 
-			result->allocator = 0;
-			result->prev = 0;
-			result->next = 0;
+			result->allocator = PUGIXML_NULL;
+			result->prev = PUGIXML_NULL;
+			result->next = PUGIXML_NULL;
 			result->busy_size = 0;
 			result->freed_size = 0;
 
 		#ifdef PUGIXML_COMPACT
-			result->compact_string_base = 0;
-			result->compact_shared_parent = 0;
-			result->compact_page_marker = 0;
+			result->compact_string_base = PUGIXML_NULL;
+			result->compact_shared_parent = PUGIXML_NULL;
+			result->compact_page_marker = PUGIXML_NULL;
 		#endif
 
 			return result;
@@ -514,7 +514,7 @@ PUGI__NS_BEGIN
 		xml_allocator(xml_memory_page* root): _root(root), _busy_size(root->busy_size)
 		{
 		#ifdef PUGIXML_COMPACT
-			_hash = 0;
+			_hash = PUGIXML_NULL;
 		#endif
 		}
 
@@ -524,7 +524,7 @@ PUGI__NS_BEGIN
 
 			// allocate block with some alignment, leaving memory for worst-case padding
 			void* memory = xml_memory::allocate(size);
-			if (!memory) return 0;
+			if (!memory) return PUGIXML_NULL;
 
 			// prepare page structure
 			xml_memory_page* page = xml_memory_page::construct(memory);
@@ -561,7 +561,7 @@ PUGI__NS_BEGIN
 		void* allocate_object(size_t size, xml_memory_page*& out_page)
 		{
 			void* result = allocate_memory(size + sizeof(uint32_t), out_page);
-			if (!result) return 0;
+			if (!result) return PUGIXML_NULL;
 
 			// adjust for marker
 			ptrdiff_t offset = static_cast<char*>(result) - reinterpret_cast<char*>(out_page->compact_page_marker);
@@ -607,7 +607,7 @@ PUGI__NS_BEGIN
 
 			if (page->freed_size == page->busy_size)
 			{
-				if (page->next == 0)
+				if (page->next == PUGIXML_NULL)
 				{
 					assert(_root == page);
 
@@ -617,9 +617,9 @@ PUGI__NS_BEGIN
 
 				#ifdef PUGIXML_COMPACT
 					// reset compact state to maximize efficiency
-					page->compact_string_base = 0;
-					page->compact_shared_parent = 0;
-					page->compact_page_marker = 0;
+					page->compact_string_base = PUGIXML_NULL;
+					page->compact_shared_parent = PUGIXML_NULL;
+					page->compact_page_marker = PUGIXML_NULL;
 				#endif
 
 					_busy_size = 0;
@@ -654,7 +654,7 @@ PUGI__NS_BEGIN
 			xml_memory_page* page;
 			xml_memory_string_header* header = static_cast<xml_memory_string_header*>(allocate_memory(full_size, page));
 
-			if (!header) return 0;
+			if (!header) return PUGIXML_NULL;
 
 			// setup header
 			ptrdiff_t page_offset = reinterpret_cast<char*>(header) - reinterpret_cast<char*>(page) - sizeof(xml_memory_page);
@@ -716,7 +716,7 @@ PUGI__NS_BEGIN
 		xml_memory_page* page = allocate_page(size <= large_allocation_threshold ? xml_memory_page_size : size);
 		out_page = page;
 
-		if (!page) return 0;
+		if (!page) return PUGIXML_NULL;
 
 		if (size <= large_allocation_threshold)
 		{
@@ -863,7 +863,7 @@ PUGI__NS_BEGIN
 					return compact_get_value<header_offset, T>(this);
 			}
 			else
-				return 0;
+				return PUGIXML_NULL;
 		}
 
 		T* operator->() const
@@ -906,7 +906,7 @@ PUGI__NS_BEGIN
 				{
 					xml_memory_page* page = compact_get_page(this, header_offset);
 
-					if (PUGI__UNLIKELY(page->compact_shared_parent == 0))
+					if (PUGI__UNLIKELY(page->compact_shared_parent == PUGIXML_NULL))
 						page->compact_shared_parent = value;
 
 					if (page->compact_shared_parent == value)
@@ -943,7 +943,7 @@ PUGI__NS_BEGIN
 					return compact_get_value<header_offset, T>(this);
 			}
 			else
-				return 0;
+				return PUGIXML_NULL;
 		}
 
 		T* operator->() const
@@ -973,7 +973,7 @@ PUGI__NS_BEGIN
 			{
 				xml_memory_page* page = compact_get_page(this, header_offset);
 
-				if (PUGI__UNLIKELY(page->compact_string_base == 0))
+				if (PUGI__UNLIKELY(page->compact_string_base == PUGIXML_NULL))
 					page->compact_string_base = value;
 
 				ptrdiff_t offset = value - page->compact_string_base;
@@ -1039,7 +1039,7 @@ PUGI__NS_BEGIN
 				}
 			}
 			else
-				return 0;
+				return PUGIXML_NULL;
 		}
 
 	private:
@@ -1098,7 +1098,7 @@ namespace pugi
 {
 	struct xml_attribute_struct
 	{
-		xml_attribute_struct(impl::xml_memory_page* page): name(0), value(0), prev_attribute_c(0), next_attribute(0)
+		xml_attribute_struct(impl::xml_memory_page* page): name(PUGIXML_NULL), value(PUGIXML_NULL), prev_attribute_c(PUGIXML_NULL), next_attribute(PUGIXML_NULL)
 		{
 			header = PUGI__GETHEADER_IMPL(this, page, 0);
 		}
@@ -1114,7 +1114,7 @@ namespace pugi
 
 	struct xml_node_struct
 	{
-		xml_node_struct(impl::xml_memory_page* page, xml_node_type type): name(0), value(0), parent(0), first_child(0), prev_sibling_c(0), next_sibling(0), first_attribute(0)
+		xml_node_struct(impl::xml_memory_page* page, xml_node_type type): name(PUGIXML_NULL), value(PUGIXML_NULL), parent(PUGIXML_NULL), first_child(PUGIXML_NULL), prev_sibling_c(PUGIXML_NULL), next_sibling(PUGIXML_NULL), first_attribute(PUGIXML_NULL)
 		{
 			header = PUGI__GETHEADER_IMPL(this, page, type);
 		}
@@ -1145,7 +1145,7 @@ PUGI__NS_BEGIN
 
 	struct xml_document_struct: public xml_node_struct, public xml_allocator
 	{
-		xml_document_struct(xml_memory_page* page): xml_node_struct(page, node_document), xml_allocator(page), buffer(0), extra_buffers(0)
+		xml_document_struct(xml_memory_page* page): xml_node_struct(page, node_document), xml_allocator(page), buffer(PUGIXML_NULL), extra_buffers(PUGIXML_NULL)
 		{
 		}
 
@@ -1179,7 +1179,7 @@ PUGI__NS_BEGIN
 	{
 		xml_memory_page* page;
 		void* memory = alloc.allocate_object(sizeof(xml_attribute_struct), page);
-		if (!memory) return 0;
+		if (!memory) return PUGIXML_NULL;
 
 		return new (memory) xml_attribute_struct(page);
 	}
@@ -1188,7 +1188,7 @@ PUGI__NS_BEGIN
 	{
 		xml_memory_page* page;
 		void* memory = alloc.allocate_object(sizeof(xml_node_struct), page);
-		if (!memory) return 0;
+		if (!memory) return PUGIXML_NULL;
 
 		return new (memory) xml_node_struct(page, type);
 	}
@@ -1327,9 +1327,9 @@ PUGI__NS_BEGIN
 		else
 			parent->first_child = next;
 
-		node->parent = 0;
-		node->prev_sibling_c = 0;
-		node->next_sibling = 0;
+		node->parent = PUGIXML_NULL;
+		node->prev_sibling_c = PUGIXML_NULL;
+		node->next_sibling = PUGIXML_NULL;
 	}
 
 	inline void append_attribute(xml_attribute_struct* attr, xml_node_struct* node)
@@ -1410,16 +1410,16 @@ PUGI__NS_BEGIN
 		else
 			node->first_attribute = next;
 
-		attr->prev_attribute_c = 0;
-		attr->next_attribute = 0;
+		attr->prev_attribute_c = PUGIXML_NULL;
+		attr->next_attribute = PUGIXML_NULL;
 	}
 
 	PUGI__FN_NO_INLINE xml_node_struct* append_new_node(xml_node_struct* node, xml_allocator& alloc, xml_node_type type = node_element)
 	{
-		if (!alloc.reserve()) return 0;
+		if (!alloc.reserve()) return PUGIXML_NULL;
 
 		xml_node_struct* child = allocate_node(alloc, type);
-		if (!child) return 0;
+		if (!child) return PUGIXML_NULL;
 
 		append_node(child, node);
 
@@ -1428,10 +1428,10 @@ PUGI__NS_BEGIN
 
 	PUGI__FN_NO_INLINE xml_attribute_struct* append_new_attribute(xml_node_struct* node, xml_allocator& alloc)
 	{
-		if (!alloc.reserve()) return 0;
+		if (!alloc.reserve()) return PUGIXML_NULL;
 
 		xml_attribute_struct* attr = allocate_attribute(alloc);
-		if (!attr) return 0;
+		if (!attr) return PUGIXML_NULL;
 
 		append_attribute(attr, node);
 
@@ -2013,7 +2013,7 @@ PUGI__NS_BEGIN
 		if (d0 == 0x3c && d1 == 0) return encoding_utf16_le;
 
 		// no known BOM detected; parse declaration
-		const uint8_t* enc = 0;
+		const uint8_t* enc = PUGIXML_NULL;
 		size_t enc_length = 0;
 
 		if (d0 == 0x3c && d1 == 0x3f && d2 == 0x78 && d3 == 0x6d && parse_declaration_encoding(data, size, enc, enc_length))
@@ -2382,7 +2382,7 @@ PUGI__NS_BEGIN
 			if (header & header_mask) alloc->deallocate_string(dest);
 
 			// mark the string as not allocated
-			dest = 0;
+			dest = PUGIXML_NULL;
 			header &= ~header_mask;
 
 			return true;
@@ -2425,7 +2425,7 @@ PUGI__NS_BEGIN
 		char_t* end;
 		size_t size;
 
-		gap(): end(0), size(0)
+		gap(): end(PUGIXML_NULL), size(0)
 		{
 		}
 
@@ -2612,7 +2612,7 @@ PUGI__NS_BEGIN
 	#define PUGI__SCANWHILE(X)          { while (X) ++s; }
 	#define PUGI__SCANWHILE_UNROLL(X)   { for (;;) { char_t ss = s[0]; if (PUGI__UNLIKELY(!(X))) { break; } ss = s[1]; if (PUGI__UNLIKELY(!(X))) { s += 1; break; } ss = s[2]; if (PUGI__UNLIKELY(!(X))) { s += 2; break; } ss = s[3]; if (PUGI__UNLIKELY(!(X))) { s += 3; break; } s += 4; } }
 	#define PUGI__ENDSEG()              { ch = *s; *s = 0; ++s; }
-	#define PUGI__THROW_ERROR(err, m)   return error_offset = m, error_status = err, static_cast<char_t*>(0)
+	#define PUGI__THROW_ERROR(err, m)   return error_offset = m, error_status = err, static_cast<char_t*>(PUGIXML_NULL)
 	#define PUGI__CHECK_ERROR(err, m)   { if (*s == 0) PUGI__THROW_ERROR(err, m); }
 
 	PUGI__FN char_t* strconv_comment(char_t* s, char_t endch)
@@ -2637,7 +2637,7 @@ PUGI__NS_BEGIN
 			}
 			else if (*s == 0)
 			{
-				return 0;
+				return PUGIXML_NULL;
 			}
 			else ++s;
 		}
@@ -2665,7 +2665,7 @@ PUGI__NS_BEGIN
 			}
 			else if (*s == 0)
 			{
-				return 0;
+				return PUGIXML_NULL;
 			}
 			else ++s;
 		}
@@ -2738,7 +2738,7 @@ PUGI__NS_BEGIN
 		case 5: return strconv_pcdata_impl<opt_true, opt_false, opt_true>::parse;
 		case 6: return strconv_pcdata_impl<opt_true, opt_true, opt_false>::parse;
 		case 7: return strconv_pcdata_impl<opt_true, opt_true, opt_true>::parse;
-		default: assert(false); return 0; // unreachable
+		default: assert(false); return PUGIXML_NULL; // unreachable
 		}
 	}
 
@@ -2792,7 +2792,7 @@ PUGI__NS_BEGIN
 				}
 				else if (!*s)
 				{
-					return 0;
+					return PUGIXML_NULL;
 				}
 				else ++s;
 			}
@@ -2828,7 +2828,7 @@ PUGI__NS_BEGIN
 				}
 				else if (!*s)
 				{
-					return 0;
+					return PUGIXML_NULL;
 				}
 				else ++s;
 			}
@@ -2860,7 +2860,7 @@ PUGI__NS_BEGIN
 				}
 				else if (!*s)
 				{
-					return 0;
+					return PUGIXML_NULL;
 				}
 				else ++s;
 			}
@@ -2886,7 +2886,7 @@ PUGI__NS_BEGIN
 				}
 				else if (!*s)
 				{
-					return 0;
+					return PUGIXML_NULL;
 				}
 				else ++s;
 			}
@@ -2915,7 +2915,7 @@ PUGI__NS_BEGIN
 		case 13: return strconv_attribute_impl<opt_true>::parse_wnorm;
 		case 14: return strconv_attribute_impl<opt_false>::parse_wnorm;
 		case 15: return strconv_attribute_impl<opt_true>::parse_wnorm;
-		default: assert(false); return 0; // unreachable
+		default: assert(false); return PUGIXML_NULL; // unreachable
 		}
 	}
 
@@ -2934,7 +2934,7 @@ PUGI__NS_BEGIN
 		char_t* error_offset;
 		xml_parse_status error_status;
 
-		xml_parser(xml_allocator* alloc_): alloc(alloc_), error_offset(0), error_status(status_ok)
+		xml_parser(xml_allocator* alloc_): alloc(alloc_), error_offset(PUGIXML_NULL), error_status(status_ok)
 		{
 		}
 
@@ -3528,7 +3528,7 @@ PUGI__NS_BEGIN
 				return make_parse_result(PUGI__OPTSET(parse_fragment) ? status_ok : status_no_document_element);
 
 			// get last child of the root before parsing
-			xml_node_struct* last_root_child = root->first_child ? root->first_child->prev_sibling_c + 0 : 0;
+			xml_node_struct* last_root_child = root->first_child ? root->first_child->prev_sibling_c + 0 : PUGIXML_NULL;
 
 			// create parser on stack
 			xml_parser parser(static_cast<xml_allocator*>(xmldoc));
@@ -4445,7 +4445,7 @@ PUGI__NS_BEGIN
 	PUGI__FN void node_copy_tree(xml_node_struct* dn, xml_node_struct* sn)
 	{
 		xml_allocator& alloc = get_allocator(dn);
-		xml_allocator* shared_alloc = (&alloc == &get_allocator(sn)) ? &alloc : 0;
+		xml_allocator* shared_alloc = (&alloc == &get_allocator(sn)) ? &alloc : PUGIXML_NULL;
 
 		node_copy_contents(dn, sn, shared_alloc);
 
@@ -4499,7 +4499,7 @@ PUGI__NS_BEGIN
 	PUGI__FN void node_copy_attribute(xml_attribute_struct* da, xml_attribute_struct* sa)
 	{
 		xml_allocator& alloc = get_allocator(da);
-		xml_allocator* shared_alloc = (&alloc == &get_allocator(sa)) ? &alloc : 0;
+		xml_allocator* shared_alloc = (&alloc == &get_allocator(sa)) ? &alloc : PUGIXML_NULL;
 
 		node_copy_string(da->name, da->header, xml_memory_page_name_allocated_mask, sa->name, sa->header, shared_alloc);
 		node_copy_string(da->value, da->header, xml_memory_page_value_allocated_mask, sa->value, sa->header, shared_alloc);
@@ -4608,18 +4608,18 @@ PUGI__NS_BEGIN
 	PUGI__FN double get_value_double(const char_t* value)
 	{
 	#ifdef PUGIXML_WCHAR_MODE
-		return wcstod(value, 0);
+		return wcstod(value, PUGIXML_NULL);
 	#else
-		return strtod(value, 0);
+		return strtod(value, PUGIXML_NULL);
 	#endif
 	}
 
 	PUGI__FN float get_value_float(const char_t* value)
 	{
 	#ifdef PUGIXML_WCHAR_MODE
-		return static_cast<float>(wcstod(value, 0));
+		return static_cast<float>(wcstod(value, PUGIXML_NULL));
 	#else
-		return static_cast<float>(strtod(value, 0));
+		return static_cast<float>(strtod(value, PUGIXML_NULL));
 	#endif
 	}
 
@@ -4724,10 +4724,10 @@ PUGI__NS_BEGIN
 		xml_encoding buffer_encoding = impl::get_buffer_encoding(encoding, contents, size);
 
 		// if convert_buffer below throws bad_alloc, we still need to deallocate contents if we own it
-		auto_deleter<void> contents_guard(own ? contents : 0, xml_memory::deallocate);
+		auto_deleter<void> contents_guard(own ? contents : PUGIXML_NULL, xml_memory::deallocate);
 
 		// get private buffer
-		char_t* buffer = 0;
+		char_t* buffer = PUGIXML_NULL;
 		size_t length = 0;
 
 		// coverity[var_deref_model]
@@ -4859,7 +4859,7 @@ PUGI__NS_BEGIN
 		static xml_stream_chunk* create()
 		{
 			void* memory = xml_memory::allocate(sizeof(xml_stream_chunk));
-			if (!memory) return 0;
+			if (!memory) return PUGIXML_NULL;
 
 			return new (memory) xml_stream_chunk();
 		}
@@ -4877,7 +4877,7 @@ PUGI__NS_BEGIN
 			}
 		}
 
-		xml_stream_chunk(): next(0), size(0)
+		xml_stream_chunk(): next(PUGIXML_NULL), size(0)
 		{
 		}
 
@@ -4889,11 +4889,11 @@ PUGI__NS_BEGIN
 
 	template <typename T> PUGI__FN xml_parse_status load_stream_data_noseek(std::basic_istream<T>& stream, void** out_buffer, size_t* out_size)
 	{
-		auto_deleter<xml_stream_chunk<T> > chunks(0, xml_stream_chunk<T>::destroy);
+		auto_deleter<xml_stream_chunk<T> > chunks(PUGIXML_NULL, xml_stream_chunk<T>::destroy);
 
 		// read file to a chunk list
 		size_t total = 0;
-		xml_stream_chunk<T>* last = 0;
+		xml_stream_chunk<T>* last = PUGIXML_NULL;
 
 		while (!stream.eof())
 		{
@@ -4979,7 +4979,7 @@ PUGI__NS_BEGIN
 
 	template <typename T> PUGI__FN xml_parse_result load_stream_impl(xml_document_struct* doc, std::basic_istream<T>& stream, unsigned int options, xml_encoding encoding, char_t** out_buffer)
 	{
-		void* buffer = 0;
+		void* buffer = PUGIXML_NULL;
 		size_t size = 0;
 		xml_parse_status status = status_ok;
 
@@ -5024,7 +5024,7 @@ PUGI__NS_BEGIN
 
 		// allocate resulting string
 		char* result = static_cast<char*>(xml_memory::allocate(size + 1));
-		if (!result) return 0;
+		if (!result) return PUGIXML_NULL;
 
 		// second pass: convert to utf8
 		as_utf8_end(result, size, str, length);
@@ -5039,7 +5039,7 @@ PUGI__NS_BEGIN
 	{
 		// there is no standard function to open wide paths, so our best bet is to try utf8 path
 		char* path_utf8 = convert_path_heap(path);
-		if (!path_utf8) return 0;
+		if (!path_utf8) return PUGIXML_NULL;
 
 		// convert mode to ASCII (we mirror _wfopen interface)
 		char mode_ascii[4] = {0};
@@ -5082,7 +5082,7 @@ PUGI__NS_BEGIN
 
 		name_null_sentry(xml_node_struct* node_): node(node_), name(node_->name)
 		{
-			node->name = 0;
+			node->name = PUGIXML_NULL;
 		}
 
 		~name_null_sentry()
@@ -5105,11 +5105,11 @@ namespace pugi
 	}
 
 #ifndef PUGIXML_NO_STL
-	PUGI__FN xml_writer_stream::xml_writer_stream(std::basic_ostream<char, std::char_traits<char> >& stream): narrow_stream(&stream), wide_stream(0)
+	PUGI__FN xml_writer_stream::xml_writer_stream(std::basic_ostream<char, std::char_traits<char> >& stream): narrow_stream(&stream), wide_stream(PUGIXML_NULL)
 	{
 	}
 
-	PUGI__FN xml_writer_stream::xml_writer_stream(std::basic_ostream<wchar_t, std::char_traits<wchar_t> >& stream): narrow_stream(0), wide_stream(&stream)
+	PUGI__FN xml_writer_stream::xml_writer_stream(std::basic_ostream<wchar_t, std::char_traits<wchar_t> >& stream): narrow_stream(PUGIXML_NULL), wide_stream(&stream)
 	{
 	}
 
@@ -5153,7 +5153,7 @@ namespace pugi
 		return true;
 	}
 
-	PUGI__FN xml_attribute::xml_attribute(): _attr(0)
+	PUGI__FN xml_attribute::xml_attribute(): _attr(PUGIXML_NULL)
 	{
 	}
 
@@ -5167,7 +5167,7 @@ namespace pugi
 
 	PUGI__FN xml_attribute::operator xml_attribute::unspecified_bool_type() const
 	{
-		return _attr ? unspecified_bool_xml_attribute : 0;
+		return _attr ? unspecified_bool_xml_attribute : PUGIXML_NULL;
 	}
 
 	PUGI__FN bool xml_attribute::operator!() const
@@ -5479,7 +5479,7 @@ namespace pugi
 	}
 #endif
 
-	PUGI__FN xml_node::xml_node(): _root(0)
+	PUGI__FN xml_node::xml_node(): _root(PUGIXML_NULL)
 	{
 	}
 
@@ -5493,7 +5493,7 @@ namespace pugi
 
 	PUGI__FN xml_node::operator xml_node::unspecified_bool_type() const
 	{
-		return _root ? unspecified_bool_xml_node : 0;
+		return _root ? unspecified_bool_xml_node : PUGIXML_NULL;
 	}
 
 	PUGI__FN bool xml_node::operator!() const
@@ -5503,22 +5503,22 @@ namespace pugi
 
 	PUGI__FN xml_node::iterator xml_node::begin() const
 	{
-		return iterator(_root ? _root->first_child + 0 : 0, _root);
+		return iterator(_root ? _root->first_child + 0 : PUGIXML_NULL, _root);
 	}
 
 	PUGI__FN xml_node::iterator xml_node::end() const
 	{
-		return iterator(0, _root);
+		return iterator(PUGIXML_NULL, _root);
 	}
 
 	PUGI__FN xml_node::attribute_iterator xml_node::attributes_begin() const
 	{
-		return attribute_iterator(_root ? _root->first_attribute + 0 : 0, _root);
+		return attribute_iterator(_root ? _root->first_attribute + 0 : PUGIXML_NULL, _root);
 	}
 
 	PUGI__FN xml_node::attribute_iterator xml_node::attributes_end() const
 	{
-		return attribute_iterator(0, _root);
+		return attribute_iterator(PUGIXML_NULL, _root);
 	}
 
 	PUGI__FN xml_object_range<xml_node_iterator> xml_node::children() const
@@ -5528,7 +5528,7 @@ namespace pugi
 
 	PUGI__FN xml_object_range<xml_named_node_iterator> xml_node::children(const char_t* name_) const
 	{
-		return xml_object_range<xml_named_node_iterator>(xml_named_node_iterator(child(name_)._root, _root, name_), xml_named_node_iterator(0, _root, name_));
+		return xml_object_range<xml_named_node_iterator>(xml_named_node_iterator(child(name_)._root, _root, name_), xml_named_node_iterator(PUGIXML_NULL, _root, name_));
 	}
 
 	PUGI__FN xml_object_range<xml_attribute_iterator> xml_node::attributes() const
@@ -6210,7 +6210,7 @@ namespace pugi
 			attr = next;
 		}
 
-		_root->first_attribute = 0;
+		_root->first_attribute = PUGIXML_NULL;
 
 		return true;
 	}
@@ -6249,7 +6249,7 @@ namespace pugi
 			cur = next;
 		}
 
-		_root->first_child = 0;
+		_root->first_child = PUGIXML_NULL;
 
 		return true;
 	}
@@ -6266,7 +6266,7 @@ namespace pugi
 		doc->header |= impl::xml_memory_page_contents_shared_mask;
 
 		// get extra buffer element (we'll store the document fragment buffer there so that we can deallocate it later)
-		impl::xml_memory_page* page = 0;
+		impl::xml_memory_page* page = PUGIXML_NULL;
 		impl::xml_extra_buffer* extra = static_cast<impl::xml_extra_buffer*>(doc->allocate_memory(sizeof(impl::xml_extra_buffer) + sizeof(void*), page));
 		(void)page;
 
@@ -6279,11 +6279,11 @@ namespace pugi
 	#endif
 
 		// add extra buffer to the list
-		extra->buffer = 0;
+		extra->buffer = PUGIXML_NULL;
 		extra->next = doc->extra_buffers;
 		doc->extra_buffers = extra;
 
-		// name of the root has to be NULL before parsing - otherwise closing node mismatches will not be detected at the top level
+		// name of the root has to be PUGIXML_NULL before parsing - otherwise closing node mismatches will not be detected at the top level
 		impl::name_null_sentry sentry(_root);
 
 		return impl::load_buffer_impl(doc, _root, const_cast<void*>(contents), size, options, encoding, false, false, &extra->buffer);
@@ -6419,7 +6419,7 @@ namespace pugi
 		xml_node arg_begin(_root);
 		if (!walker.begin(arg_begin)) return false;
 
-		xml_node_struct* cur = _root ? _root->first_child + 0 : 0;
+		xml_node_struct* cur = _root ? _root->first_child + 0 : PUGIXML_NULL;
 
 		if (cur)
 		{
@@ -6555,7 +6555,7 @@ namespace pugi
 			if (impl::is_text_node(node))
 				return node;
 
-		return 0;
+		return PUGIXML_NULL;
 	}
 
 	PUGI__FN xml_node_struct* xml_text::_data_new()
@@ -6566,7 +6566,7 @@ namespace pugi
 		return xml_node(_root).append_child(node_pcdata).internal_object();
 	}
 
-	PUGI__FN xml_text::xml_text(): _root(0)
+	PUGI__FN xml_text::xml_text(): _root(PUGIXML_NULL)
 	{
 	}
 
@@ -6576,7 +6576,7 @@ namespace pugi
 
 	PUGI__FN xml_text::operator xml_text::unspecified_bool_type() const
 	{
-		return _data() ? unspecified_bool_xml_text : 0;
+		return _data() ? unspecified_bool_xml_text : PUGIXML_NULL;
 	}
 
 	PUGI__FN bool xml_text::operator!() const
@@ -6586,7 +6586,7 @@ namespace pugi
 
 	PUGI__FN bool xml_text::empty() const
 	{
-		return _data() == 0;
+		return _data() == PUGIXML_NULL;
 	}
 
 	PUGI__FN const char_t* xml_text::get() const
@@ -6957,7 +6957,7 @@ namespace pugi
 		return temp;
 	}
 
-	PUGI__FN xml_named_node_iterator::xml_named_node_iterator(): _name(0)
+	PUGI__FN xml_named_node_iterator::xml_named_node_iterator(): _name(PUGIXML_NULL)
 	{
 	}
 
@@ -7067,7 +7067,7 @@ namespace pugi
 		}
 	}
 
-	PUGI__FN xml_document::xml_document(): _buffer(0)
+	PUGI__FN xml_document::xml_document(): _buffer(PUGIXML_NULL)
 	{
 		_create();
 	}
@@ -7078,7 +7078,7 @@ namespace pugi
 	}
 
 #ifdef PUGIXML_HAS_MOVE
-	PUGI__FN xml_document::xml_document(xml_document&& rhs) PUGIXML_NOEXCEPT_IF_NOT_COMPACT: _buffer(0)
+	PUGI__FN xml_document::xml_document(xml_document&& rhs) PUGIXML_NOEXCEPT_IF_NOT_COMPACT: _buffer(PUGIXML_NULL)
 	{
 		_create();
 		_move(rhs);
@@ -7160,7 +7160,7 @@ namespace pugi
 		if (_buffer)
 		{
 			impl::xml_memory::deallocate(_buffer);
-			_buffer = 0;
+			_buffer = PUGIXML_NULL;
 		}
 
 		// destroy extra buffers (note: no need to destroy linked list nodes, they're allocated using document allocator)
@@ -7188,7 +7188,7 @@ namespace pugi
 		static_cast<impl::xml_document_struct*>(_root)->hash.clear();
 	#endif
 
-		_root = 0;
+		_root = PUGIXML_NULL;
 	}
 
 #ifdef PUGIXML_HAS_MOVE
@@ -7243,7 +7243,7 @@ namespace pugi
 		doc->_hash = &doc->hash;
 
 		// make sure we don't access other hash up until the end when we reinitialize other document
-		other->_hash = 0;
+		other->_hash = PUGIXML_NULL;
 	#endif
 
 		// move page structure
@@ -7261,7 +7261,7 @@ namespace pugi
 			page->prev = doc_page;
 
 			doc_page->next = page;
-			other_page->next = 0;
+			other_page->next = PUGIXML_NULL;
 		}
 
 		// make sure pages point to the correct document state
@@ -7298,7 +7298,7 @@ namespace pugi
 
 		// reset other document
 		new (other) impl::xml_document_struct(PUGI__GETPAGE(other));
-		rhs._buffer = 0;
+		rhs._buffer = PUGIXML_NULL;
 	}
 #endif
 
@@ -7725,7 +7725,7 @@ PUGI__NS_BEGIN
 
 		for (size_t probe = 0; probe <= hashmod; ++probe)
 		{
-			if (table[bucket] == 0)
+			if (table[bucket] == PUGIXML_NULL)
 			{
 				table[bucket] = key;
 				return true;
@@ -7773,7 +7773,7 @@ PUGI__NS_BEGIN
 		size_t _root_size;
 		bool* _error;
 
-		xpath_allocator(xpath_memory_block* root, bool* error = 0): _root(root), _root_size(0), _error(error)
+		xpath_allocator(xpath_memory_block* root, bool* error = PUGIXML_NULL): _root(root), _root_size(0), _error(error)
 		{
 		}
 
@@ -7801,7 +7801,7 @@ PUGI__NS_BEGIN
 				if (!block)
 				{
 					if (_error) *_error = true;
-					return 0;
+					return PUGIXML_NULL;
 				}
 
 				block->next = _root;
@@ -7821,7 +7821,7 @@ PUGI__NS_BEGIN
 			new_size = (new_size + xpath_memory_block_alignment - 1) & ~(xpath_memory_block_alignment - 1);
 
 			// we can only reallocate the last object
-			assert(ptr == 0 || static_cast<char*>(ptr) + old_size == &_root->data[0] + _root_size);
+			assert(ptr == PUGIXML_NULL || static_cast<char*>(ptr) + old_size == &_root->data[0] + _root_size);
 
 			// try to reallocate the object inplace
 			if (ptr && _root_size - old_size + new_size <= _root->capacity)
@@ -7832,7 +7832,7 @@ PUGI__NS_BEGIN
 
 			// allocate a new block
 			void* result = allocate(new_size);
-			if (!result) return 0;
+			if (!result) return PUGIXML_NULL;
 
 			// we have a new block
 			if (ptr)
@@ -7927,7 +7927,7 @@ PUGI__NS_BEGIN
 
 		xpath_stack_data(): result(blocks + 0, &oom), temp(blocks + 1, &oom), oom(false)
 		{
-			blocks[0].next = blocks[1].next = 0;
+			blocks[0].next = blocks[1].next = PUGIXML_NULL;
 			blocks[0].capacity = blocks[1].capacity = sizeof(blocks[0].data);
 
 			stack.result = &result;
@@ -7953,7 +7953,7 @@ PUGI__NS_BEGIN
 		static char_t* duplicate_string(const char_t* string, size_t length, xpath_allocator* alloc)
 		{
 			char_t* result = static_cast<char_t*>(alloc->allocate((length + 1) * sizeof(char_t)));
-			if (!result) return 0;
+			if (!result) return PUGIXML_NULL;
 
 			memcpy(result, string, length * sizeof(char_t));
 			result[length] = 0;
@@ -8013,7 +8013,7 @@ PUGI__NS_BEGIN
 				size_t result_length = target_length + source_length;
 
 				// allocate new buffer
-				char_t* result = static_cast<char_t*>(alloc->reallocate(_uses_heap ? const_cast<char_t*>(_buffer) : 0, (target_length + 1) * sizeof(char_t), (result_length + 1) * sizeof(char_t)));
+				char_t* result = static_cast<char_t*>(alloc->reallocate(_uses_heap ? const_cast<char_t*>(_buffer) : PUGIXML_NULL, (target_length + 1) * sizeof(char_t), (result_length + 1) * sizeof(char_t)));
 				if (!result) return;
 
 				// append first string to the new buffer in case there was no reallocation
@@ -8048,7 +8048,7 @@ PUGI__NS_BEGIN
 				size_t length_ = strlength(_buffer);
 				const char_t* data_ = duplicate_string(_buffer, length_, alloc);
 
-				if (!data_) return 0;
+				if (!data_) return PUGIXML_NULL;
 
 				_buffer = data_;
 				_uses_heap = true;
@@ -8257,7 +8257,7 @@ PUGI__NS_BEGIN
 				if (node->value && (node->header & impl::xml_memory_page_value_allocated_or_shared_mask) == 0) return node->value;
 			}
 
-			return 0;
+			return PUGIXML_NULL;
 		}
 
 		xml_attribute_struct* attr = xnode.attribute().internal_object();
@@ -8270,10 +8270,10 @@ PUGI__NS_BEGIN
 				if ((attr->header & impl::xml_memory_page_value_allocated_or_shared_mask) == 0) return attr->value;
 			}
 
-			return 0;
+			return PUGIXML_NULL;
 		}
 
-		return 0;
+		return PUGIXML_NULL;
 	}
 
 	struct document_order_comparator
@@ -8377,7 +8377,7 @@ PUGI__NS_BEGIN
 			return PUGIXML_TEXT("0");
 
 		default:
-			return 0;
+			return PUGIXML_NULL;
 		}
 	#else
 		// fallback
@@ -8386,7 +8386,7 @@ PUGI__NS_BEGIN
 		if (v == 0) return PUGIXML_TEXT("0");
 		if (v != v) return PUGIXML_TEXT("NaN");
 		if (v * 2 == v) return value > 0 ? PUGIXML_TEXT("Infinity") : PUGIXML_TEXT("-Infinity");
-		return 0;
+		return PUGIXML_NULL;
 	#endif
 	}
 
@@ -8551,9 +8551,9 @@ PUGI__NS_BEGIN
 
 		// parse string
 	#ifdef PUGIXML_WCHAR_MODE
-		return wcstod(string, 0);
+		return wcstod(string, PUGIXML_NULL);
 	#else
-		return strtod(string, 0);
+		return strtod(string, PUGIXML_NULL);
 	#endif
 	}
 
@@ -8615,7 +8615,7 @@ PUGI__NS_BEGIN
 		{
 			const char_t* pos = find_char(name, ':');
 
-			prefix = pos ? name : 0;
+			prefix = pos ? name : PUGIXML_NULL;
 			prefix_length = pos ? static_cast<size_t>(pos - name) : 0;
 		}
 
@@ -8733,7 +8733,7 @@ PUGI__NS_BEGIN
 			unsigned int tc = static_cast<unsigned int>(*to);
 
 			if (fc >= 128 || tc >= 128)
-				return 0;
+				return PUGIXML_NULL;
 
 			// code=128 means "skip character"
 			if (!table[fc])
@@ -8748,7 +8748,7 @@ PUGI__NS_BEGIN
 				table[i] = static_cast<unsigned char>(i);
 
 		void* result = alloc->allocate(sizeof(table));
-		if (!result) return 0;
+		if (!result) return PUGIXML_NULL;
 
 		memcpy(result, table, sizeof(table));
 
@@ -8812,7 +8812,7 @@ PUGI__NS_BEGIN
 
 	struct xpath_variable_string: xpath_variable
 	{
-		xpath_variable_string(): xpath_variable(xpath_type_string), value(0)
+		xpath_variable_string(): xpath_variable(xpath_type_string), value(PUGIXML_NULL)
 		{
 		}
 
@@ -8859,11 +8859,11 @@ PUGI__NS_BEGIN
 	template <typename T> PUGI__FN T* new_xpath_variable(const char_t* name)
 	{
 		size_t length = strlength(name);
-		if (length == 0) return 0; // empty variable names are invalid
+		if (length == 0) return PUGIXML_NULL; // empty variable names are invalid
 
 		// $$ we can't use offsetof(T, name) because T is non-POD, so we just allocate additional length characters
 		void* memory = xml_memory::allocate(sizeof(T) + length * sizeof(char_t));
-		if (!memory) return 0;
+		if (!memory) return PUGIXML_NULL;
 
 		T* result = new (memory) T();
 
@@ -8889,7 +8889,7 @@ PUGI__NS_BEGIN
 			return new_xpath_variable<xpath_variable_boolean>(name);
 
 		default:
-			return 0;
+			return PUGIXML_NULL;
 		}
 	}
 
@@ -9042,7 +9042,7 @@ PUGI__NS_BEGIN
 		xpath_node* _eos;
 
 	public:
-		xpath_node_set_raw(): _type(xpath_node_set::type_unsorted), _begin(0), _end(0), _eos(0)
+		xpath_node_set_raw(): _type(xpath_node_set::type_unsorted), _begin(PUGIXML_NULL), _end(PUGIXML_NULL), _eos(PUGIXML_NULL)
 		{
 		}
 
@@ -9234,7 +9234,7 @@ PUGI__NS_BEGIN
 		const char_t* begin;
 		const char_t* end;
 
-		xpath_lexer_string(): begin(0), end(0)
+		xpath_lexer_string(): begin(PUGIXML_NULL), end(PUGIXML_NULL)
 		{
 		}
 
@@ -10421,40 +10421,40 @@ PUGI__NS_BEGIN
 
 	public:
 		xpath_ast_node(ast_type_t type, xpath_value_type rettype_, const char_t* value):
-			_type(static_cast<char>(type)), _rettype(static_cast<char>(rettype_)), _axis(0), _test(0), _left(0), _right(0), _next(0)
+			_type(static_cast<char>(type)), _rettype(static_cast<char>(rettype_)), _axis(0), _test(0), _left(PUGIXML_NULL), _right(PUGIXML_NULL), _next(PUGIXML_NULL)
 		{
 			assert(type == ast_string_constant);
 			_data.string = value;
 		}
 
 		xpath_ast_node(ast_type_t type, xpath_value_type rettype_, double value):
-			_type(static_cast<char>(type)), _rettype(static_cast<char>(rettype_)), _axis(0), _test(0), _left(0), _right(0), _next(0)
+			_type(static_cast<char>(type)), _rettype(static_cast<char>(rettype_)), _axis(0), _test(0), _left(PUGIXML_NULL), _right(PUGIXML_NULL), _next(PUGIXML_NULL)
 		{
 			assert(type == ast_number_constant);
 			_data.number = value;
 		}
 
 		xpath_ast_node(ast_type_t type, xpath_value_type rettype_, xpath_variable* value):
-			_type(static_cast<char>(type)), _rettype(static_cast<char>(rettype_)), _axis(0), _test(0), _left(0), _right(0), _next(0)
+			_type(static_cast<char>(type)), _rettype(static_cast<char>(rettype_)), _axis(0), _test(0), _left(PUGIXML_NULL), _right(PUGIXML_NULL), _next(PUGIXML_NULL)
 		{
 			assert(type == ast_variable);
 			_data.variable = value;
 		}
 
-		xpath_ast_node(ast_type_t type, xpath_value_type rettype_, xpath_ast_node* left = 0, xpath_ast_node* right = 0):
-			_type(static_cast<char>(type)), _rettype(static_cast<char>(rettype_)), _axis(0), _test(0), _left(left), _right(right), _next(0)
+		xpath_ast_node(ast_type_t type, xpath_value_type rettype_, xpath_ast_node* left = PUGIXML_NULL, xpath_ast_node* right = PUGIXML_NULL):
+			_type(static_cast<char>(type)), _rettype(static_cast<char>(rettype_)), _axis(0), _test(0), _left(left), _right(right), _next(PUGIXML_NULL)
 		{
 		}
 
 		xpath_ast_node(ast_type_t type, xpath_ast_node* left, axis_t axis, nodetest_t test, const char_t* contents):
-			_type(static_cast<char>(type)), _rettype(xpath_type_node_set), _axis(static_cast<char>(axis)), _test(static_cast<char>(test)), _left(left), _right(0), _next(0)
+			_type(static_cast<char>(type)), _rettype(xpath_type_node_set), _axis(static_cast<char>(axis)), _test(static_cast<char>(test)), _left(left), _right(PUGIXML_NULL), _next(PUGIXML_NULL)
 		{
 			assert(type == ast_step);
 			_data.nodetest = contents;
 		}
 
 		xpath_ast_node(ast_type_t type, xpath_ast_node* left, xpath_ast_node* right, predicate_t test):
-			_type(static_cast<char>(type)), _rettype(xpath_type_node_set), _axis(0), _test(static_cast<char>(test)), _left(left), _right(right), _next(0)
+			_type(static_cast<char>(type)), _rettype(xpath_type_node_set), _axis(0), _test(static_cast<char>(test)), _left(left), _right(right), _next(PUGIXML_NULL)
 		{
 			assert(type == ast_filter || type == ast_predicate);
 		}
@@ -10514,7 +10514,7 @@ PUGI__NS_BEGIN
 				xpath_string lr = _left->eval_string(c, stack);
 				xpath_string rr = _right->eval_string(c, stack);
 
-				return find_substring(lr.c_str(), rr.c_str()) != 0;
+				return find_substring(lr.c_str(), rr.c_str()) != PUGIXML_NULL;
 			}
 
 			case ast_func_boolean:
@@ -11323,7 +11323,7 @@ PUGI__NS_BEGIN
 			_result->error = message;
 			_result->offset = _lexer.current_pos() - _query;
 
-			return 0;
+			return PUGIXML_NULL;
 		}
 
 		xpath_ast_node* error_oom()
@@ -11331,7 +11331,7 @@ PUGI__NS_BEGIN
 			assert(_alloc->_error);
 			*_alloc->_error = true;
 
-			return 0;
+			return PUGIXML_NULL;
 		}
 
 		xpath_ast_node* error_rec()
@@ -11347,37 +11347,37 @@ PUGI__NS_BEGIN
 		xpath_ast_node* alloc_node(ast_type_t type, xpath_value_type rettype, const char_t* value)
 		{
 			void* memory = alloc_node();
-			return memory ? new (memory) xpath_ast_node(type, rettype, value) : 0;
+			return memory ? new (memory) xpath_ast_node(type, rettype, value) : PUGIXML_NULL;
 		}
 
 		xpath_ast_node* alloc_node(ast_type_t type, xpath_value_type rettype, double value)
 		{
 			void* memory = alloc_node();
-			return memory ? new (memory) xpath_ast_node(type, rettype, value) : 0;
+			return memory ? new (memory) xpath_ast_node(type, rettype, value) : PUGIXML_NULL;
 		}
 
 		xpath_ast_node* alloc_node(ast_type_t type, xpath_value_type rettype, xpath_variable* value)
 		{
 			void* memory = alloc_node();
-			return memory ? new (memory) xpath_ast_node(type, rettype, value) : 0;
+			return memory ? new (memory) xpath_ast_node(type, rettype, value) : PUGIXML_NULL;
 		}
 
-		xpath_ast_node* alloc_node(ast_type_t type, xpath_value_type rettype, xpath_ast_node* left = 0, xpath_ast_node* right = 0)
+		xpath_ast_node* alloc_node(ast_type_t type, xpath_value_type rettype, xpath_ast_node* left = PUGIXML_NULL, xpath_ast_node* right = PUGIXML_NULL)
 		{
 			void* memory = alloc_node();
-			return memory ? new (memory) xpath_ast_node(type, rettype, left, right) : 0;
+			return memory ? new (memory) xpath_ast_node(type, rettype, left, right) : PUGIXML_NULL;
 		}
 
 		xpath_ast_node* alloc_node(ast_type_t type, xpath_ast_node* left, axis_t axis, nodetest_t test, const char_t* contents)
 		{
 			void* memory = alloc_node();
-			return memory ? new (memory) xpath_ast_node(type, left, axis, test, contents) : 0;
+			return memory ? new (memory) xpath_ast_node(type, left, axis, test, contents) : PUGIXML_NULL;
 		}
 
 		xpath_ast_node* alloc_node(ast_type_t type, xpath_ast_node* left, xpath_ast_node* right, predicate_t test)
 		{
 			void* memory = alloc_node();
-			return memory ? new (memory) xpath_ast_node(type, left, right, test) : 0;
+			return memory ? new (memory) xpath_ast_node(type, left, right, test) : PUGIXML_NULL;
 		}
 
 		const char_t* alloc_string(const xpath_lexer_string& value)
@@ -11388,7 +11388,7 @@ PUGI__NS_BEGIN
 			size_t length = static_cast<size_t>(value.end - value.begin);
 
 			char_t* c = static_cast<char_t*>(_alloc->allocate((length + 1) * sizeof(char_t)));
-			if (!c) return 0;
+			if (!c) return PUGIXML_NULL;
 
 			memcpy(c, value.begin, length * sizeof(char_t));
 			c[length] = 0;
@@ -11631,7 +11631,7 @@ PUGI__NS_BEGIN
 				if (!_variables)
 					return error("Unknown variable: variable set is not provided");
 
-				xpath_variable* var = 0;
+				xpath_variable* var = PUGIXML_NULL;
 				if (!get_variable_scratch(_scratch, _variables, name.begin, name.end, &var))
 					return error_oom();
 
@@ -11648,7 +11648,7 @@ PUGI__NS_BEGIN
 				_lexer.next();
 
 				xpath_ast_node* n = parse_expression();
-				if (!n) return 0;
+				if (!n) return PUGIXML_NULL;
 
 				if (_lexer.current() != lex_close_brace)
 					return error("Expected ')' to match an opening '('");
@@ -11661,7 +11661,7 @@ PUGI__NS_BEGIN
 			case lex_quoted_string:
 			{
 				const char_t* value = alloc_string(_lexer.contents());
-				if (!value) return 0;
+				if (!value) return PUGIXML_NULL;
 
 				_lexer.next();
 
@@ -11682,13 +11682,13 @@ PUGI__NS_BEGIN
 
 			case lex_string:
 			{
-				xpath_ast_node* args[2] = {0};
+				xpath_ast_node* args[2] = {PUGIXML_NULL};
 				size_t argc = 0;
 
 				xpath_lexer_string function = _lexer.contents();
 				_lexer.next();
 
-				xpath_ast_node* last_arg = 0;
+				xpath_ast_node* last_arg = PUGIXML_NULL;
 
 				if (_lexer.current() != lex_open_brace)
 					return error("Unrecognized function call");
@@ -11709,7 +11709,7 @@ PUGI__NS_BEGIN
 						return error_rec();
 
 					xpath_ast_node* n = parse_expression();
-					if (!n) return 0;
+					if (!n) return PUGIXML_NULL;
 
 					if (argc < 2) args[argc] = n;
 					else last_arg->set_next(n);
@@ -11736,7 +11736,7 @@ PUGI__NS_BEGIN
 		xpath_ast_node* parse_filter_expression()
 		{
 			xpath_ast_node* n = parse_primary_expression();
-			if (!n) return 0;
+			if (!n) return PUGIXML_NULL;
 
 			size_t old_depth = _depth;
 
@@ -11751,10 +11751,10 @@ PUGI__NS_BEGIN
 					return error("Predicate has to be applied to node set");
 
 				xpath_ast_node* expr = parse_expression();
-				if (!expr) return 0;
+				if (!expr) return PUGIXML_NULL;
 
 				n = alloc_node(ast_filter, n, expr, predicate_default);
-				if (!n) return 0;
+				if (!n) return PUGIXML_NULL;
 
 				if (_lexer.current() != lex_close_square_brace)
 					return error("Expected ']' to match an opening '['");
@@ -11794,7 +11794,7 @@ PUGI__NS_BEGIN
 				if (_lexer.current() == lex_open_square_brace)
 					return error("Predicates are not allowed after an abbreviated step");
 
-				return alloc_node(ast_step, set, axis_self, nodetest_type_node, 0);
+				return alloc_node(ast_step, set, axis_self, nodetest_type_node, PUGIXML_NULL);
 			}
 			else if (_lexer.current() == lex_double_dot)
 			{
@@ -11803,7 +11803,7 @@ PUGI__NS_BEGIN
 				if (_lexer.current() == lex_open_square_brace)
 					return error("Predicates are not allowed after an abbreviated step");
 
-				return alloc_node(ast_step, set, axis_parent, nodetest_type_node, 0);
+				return alloc_node(ast_step, set, axis_parent, nodetest_type_node, PUGIXML_NULL);
 			}
 
 			nodetest_t nt_type = nodetest_none;
@@ -11910,14 +11910,14 @@ PUGI__NS_BEGIN
 			}
 
 			const char_t* nt_name_copy = alloc_string(nt_name);
-			if (!nt_name_copy) return 0;
+			if (!nt_name_copy) return PUGIXML_NULL;
 
 			xpath_ast_node* n = alloc_node(ast_step, set, axis, nt_type, nt_name_copy);
-			if (!n) return 0;
+			if (!n) return PUGIXML_NULL;
 
 			size_t old_depth = _depth;
 
-			xpath_ast_node* last = 0;
+			xpath_ast_node* last = PUGIXML_NULL;
 
 			while (_lexer.current() == lex_open_square_brace)
 			{
@@ -11927,10 +11927,10 @@ PUGI__NS_BEGIN
 					return error_rec();
 
 				xpath_ast_node* expr = parse_expression();
-				if (!expr) return 0;
+				if (!expr) return PUGIXML_NULL;
 
-				xpath_ast_node* pred = alloc_node(ast_predicate, 0, expr, predicate_default);
-				if (!pred) return 0;
+				xpath_ast_node* pred = alloc_node(ast_predicate, PUGIXML_NULL, expr, predicate_default);
+				if (!pred) return PUGIXML_NULL;
 
 				if (_lexer.current() != lex_close_square_brace)
 					return error("Expected ']' to match an opening '['");
@@ -11951,7 +11951,7 @@ PUGI__NS_BEGIN
 		xpath_ast_node* parse_relative_location_path(xpath_ast_node* set)
 		{
 			xpath_ast_node* n = parse_step(set);
-			if (!n) return 0;
+			if (!n) return PUGIXML_NULL;
 
 			size_t old_depth = _depth;
 
@@ -11962,8 +11962,8 @@ PUGI__NS_BEGIN
 
 				if (l == lex_double_slash)
 				{
-					n = alloc_node(ast_step, n, axis_descendant_or_self, nodetest_type_node, 0);
-					if (!n) return 0;
+					n = alloc_node(ast_step, n, axis_descendant_or_self, nodetest_type_node, PUGIXML_NULL);
+					if (!n) return PUGIXML_NULL;
 
 					++_depth;
 				}
@@ -11972,7 +11972,7 @@ PUGI__NS_BEGIN
 					return error_rec();
 
 				n = parse_step(n);
-				if (!n) return 0;
+				if (!n) return PUGIXML_NULL;
 			}
 
 			_depth = old_depth;
@@ -11989,7 +11989,7 @@ PUGI__NS_BEGIN
 				_lexer.next();
 
 				xpath_ast_node* n = alloc_node(ast_step_root, xpath_type_node_set);
-				if (!n) return 0;
+				if (!n) return PUGIXML_NULL;
 
 				// relative location path can start from axis_attribute, dot, double_dot, multiply and string lexemes; any other lexeme means standalone root path
 				lexeme_t l = _lexer.current();
@@ -12004,16 +12004,16 @@ PUGI__NS_BEGIN
 				_lexer.next();
 
 				xpath_ast_node* n = alloc_node(ast_step_root, xpath_type_node_set);
-				if (!n) return 0;
+				if (!n) return PUGIXML_NULL;
 
-				n = alloc_node(ast_step, n, axis_descendant_or_self, nodetest_type_node, 0);
-				if (!n) return 0;
+				n = alloc_node(ast_step, n, axis_descendant_or_self, nodetest_type_node, PUGIXML_NULL);
+				if (!n) return PUGIXML_NULL;
 
 				return parse_relative_location_path(n);
 			}
 
 			// else clause moved outside of if because of bogus warning 'control may reach end of non-void function being inlined' in gcc 4.0.1
-			return parse_relative_location_path(0);
+			return parse_relative_location_path(PUGIXML_NULL);
 		}
 
 		// PathExpr ::= LocationPath
@@ -12050,7 +12050,7 @@ PUGI__NS_BEGIN
 				}
 
 				xpath_ast_node* n = parse_filter_expression();
-				if (!n) return 0;
+				if (!n) return PUGIXML_NULL;
 
 				if (_lexer.current() == lex_slash || _lexer.current() == lex_double_slash)
 				{
@@ -12062,8 +12062,8 @@ PUGI__NS_BEGIN
 						if (n->rettype() != xpath_type_node_set)
 							return error("Step has to be applied to node set");
 
-						n = alloc_node(ast_step, n, axis_descendant_or_self, nodetest_type_node, 0);
-						if (!n) return 0;
+						n = alloc_node(ast_step, n, axis_descendant_or_self, nodetest_type_node, PUGIXML_NULL);
+						if (!n) return PUGIXML_NULL;
 					}
 
 					// select from location path
@@ -12078,7 +12078,7 @@ PUGI__NS_BEGIN
 
 				// precedence 7+ - only parses union expressions
 				xpath_ast_node* n = parse_expression(7);
-				if (!n) return 0;
+				if (!n) return PUGIXML_NULL;
 
 				return alloc_node(ast_op_negate, xpath_type_number, n);
 			}
@@ -12166,14 +12166,14 @@ PUGI__NS_BEGIN
 					return error_rec();
 
 				xpath_ast_node* rhs = parse_path_or_unary_expression();
-				if (!rhs) return 0;
+				if (!rhs) return PUGIXML_NULL;
 
 				binary_op_t nextop = binary_op_t::parse(_lexer);
 
 				while (nextop.asttype != ast_unknown && nextop.precedence > op.precedence)
 				{
 					rhs = parse_expression_rec(rhs, nextop.precedence);
-					if (!rhs) return 0;
+					if (!rhs) return PUGIXML_NULL;
 
 					nextop = binary_op_t::parse(_lexer);
 				}
@@ -12182,7 +12182,7 @@ PUGI__NS_BEGIN
 					return error("Union operator has to be applied to node sets");
 
 				lhs = alloc_node(op.asttype, op.rettype, lhs, rhs);
-				if (!lhs) return 0;
+				if (!lhs) return PUGIXML_NULL;
 
 				op = binary_op_t::parse(_lexer);
 			}
@@ -12216,7 +12216,7 @@ PUGI__NS_BEGIN
 				return error_rec();
 
 			xpath_ast_node* n = parse_path_or_unary_expression();
-			if (!n) return 0;
+			if (!n) return PUGIXML_NULL;
 
 			n = parse_expression_rec(n, limit);
 
@@ -12232,7 +12232,7 @@ PUGI__NS_BEGIN
 		xpath_ast_node* parse()
 		{
 			xpath_ast_node* n = parse_expression();
-			if (!n) return 0;
+			if (!n) return PUGIXML_NULL;
 
 			assert(_depth == 0);
 
@@ -12256,7 +12256,7 @@ PUGI__NS_BEGIN
 		static xpath_query_impl* create()
 		{
 			void* memory = xml_memory::allocate(sizeof(xpath_query_impl));
-			if (!memory) return 0;
+			if (!memory) return PUGIXML_NULL;
 
 			return new (memory) xpath_query_impl();
 		}
@@ -12270,9 +12270,9 @@ PUGI__NS_BEGIN
 			xml_memory::deallocate(impl);
 		}
 
-		xpath_query_impl(): root(0), alloc(&block, &oom), oom(false)
+		xpath_query_impl(): root(PUGIXML_NULL), alloc(&block, &oom), oom(false)
 		{
-			block.next = 0;
+			block.next = PUGIXML_NULL;
 			block.capacity = sizeof(block.data);
 		}
 
@@ -12284,12 +12284,12 @@ PUGI__NS_BEGIN
 
 	PUGI__FN impl::xpath_ast_node* evaluate_node_set_prepare(xpath_query_impl* impl)
 	{
-		if (!impl) return 0;
+		if (!impl) return PUGIXML_NULL;
 
 		if (impl->root->rettype() != xpath_type_node_set)
 		{
 		#ifdef PUGIXML_NO_EXCEPTIONS
-			return 0;
+			return PUGIXML_NULL;
 		#else
 			xpath_parse_result res;
 			res.error = "Expression does not evaluate to node set";
@@ -12354,7 +12354,7 @@ namespace pugi
 
 	PUGI__FN xpath_node::operator xpath_node::unspecified_bool_type() const
 	{
-		return (_node || _attribute) ? unspecified_bool_xpath_node : 0;
+		return (_node || _attribute) ? unspecified_bool_xpath_node : PUGIXML_NULL;
 	}
 
 	PUGI__FN bool xpath_node::operator!() const
@@ -12524,7 +12524,7 @@ namespace pugi
 
 	PUGI__FN xpath_parse_result::operator bool() const
 	{
-		return error == 0;
+		return error == PUGIXML_NULL;
 	}
 
 	PUGI__FN const char* xpath_parse_result::description() const
@@ -12532,7 +12532,7 @@ namespace pugi
 		return error ? error : "No error";
 	}
 
-	PUGI__FN xpath_variable::xpath_variable(xpath_value_type type_): _type(type_), _next(0)
+	PUGI__FN xpath_variable::xpath_variable(xpath_value_type type_): _type(type_), _next(PUGIXML_NULL)
 	{
 	}
 
@@ -12554,7 +12554,7 @@ namespace pugi
 
 		default:
 			assert(false && "Invalid variable type"); // unreachable
-			return 0;
+			return PUGIXML_NULL;
 		}
 	}
 
@@ -12575,7 +12575,7 @@ namespace pugi
 
 	PUGI__FN const char_t* xpath_variable::get_string() const
 	{
-		const char_t* value = (_type == xpath_type_string) ? static_cast<const impl::xpath_variable_string*>(this)->value : 0;
+		const char_t* value = (_type == xpath_type_string) ? static_cast<const impl::xpath_variable_string*>(this)->value : PUGIXML_NULL;
 		return value ? value : PUGIXML_TEXT("");
 	}
 
@@ -12632,7 +12632,7 @@ namespace pugi
 	PUGI__FN xpath_variable_set::xpath_variable_set()
 	{
 		for (size_t i = 0; i < sizeof(_data) / sizeof(_data[0]); ++i)
-			_data[i] = 0;
+			_data[i] = PUGIXML_NULL;
 	}
 
 	PUGI__FN xpath_variable_set::~xpath_variable_set()
@@ -12644,7 +12644,7 @@ namespace pugi
 	PUGI__FN xpath_variable_set::xpath_variable_set(const xpath_variable_set& rhs)
 	{
 		for (size_t i = 0; i < sizeof(_data) / sizeof(_data[0]); ++i)
-			_data[i] = 0;
+			_data[i] = PUGIXML_NULL;
 
 		_assign(rhs);
 	}
@@ -12664,7 +12664,7 @@ namespace pugi
 		for (size_t i = 0; i < sizeof(_data) / sizeof(_data[0]); ++i)
 		{
 			_data[i] = rhs._data[i];
-			rhs._data[i] = 0;
+			rhs._data[i] = PUGIXML_NULL;
 		}
 	}
 
@@ -12675,7 +12675,7 @@ namespace pugi
 			_destroy(_data[i]);
 
 			_data[i] = rhs._data[i];
-			rhs._data[i] = 0;
+			rhs._data[i] = PUGIXML_NULL;
 		}
 
 		return *this;
@@ -12714,12 +12714,12 @@ namespace pugi
 			if (impl::strequal(var->name(), name))
 				return var;
 
-		return 0;
+		return PUGIXML_NULL;
 	}
 
 	PUGI__FN bool xpath_variable_set::_clone(xpath_variable* var, xpath_variable** out_result)
 	{
-		xpath_variable* last = 0;
+		xpath_variable* last = PUGIXML_NULL;
 
 		while (var)
 		{
@@ -12764,7 +12764,7 @@ namespace pugi
 		// look for existing variable
 		for (xpath_variable* var = _data[hash]; var; var = var->_next)
 			if (impl::strequal(var->name(), name))
-				return var->type() == type ? var : 0;
+				return var->type() == type ? var : PUGIXML_NULL;
 
 		// add new variable
 		xpath_variable* result = impl::new_xpath_variable(type, name);
@@ -12813,7 +12813,7 @@ namespace pugi
 		return _find(name);
 	}
 
-	PUGI__FN xpath_query::xpath_query(const char_t* query, xpath_variable_set* variables): _impl(0)
+	PUGI__FN xpath_query::xpath_query(const char_t* query, xpath_variable_set* variables): _impl(PUGIXML_NULL)
 	{
 		impl::xpath_query_impl* qimpl = impl::xpath_query_impl::create();
 
@@ -12837,7 +12837,7 @@ namespace pugi
 				qimpl->root->optimize(&qimpl->alloc);
 
 				_impl = impl.release();
-				_result.error = 0;
+				_result.error = PUGIXML_NULL;
 			}
 			else
 			{
@@ -12851,7 +12851,7 @@ namespace pugi
 		}
 	}
 
-	PUGI__FN xpath_query::xpath_query(): _impl(0)
+	PUGI__FN xpath_query::xpath_query(): _impl(PUGIXML_NULL)
 	{
 	}
 
@@ -12866,7 +12866,7 @@ namespace pugi
 	{
 		_impl = rhs._impl;
 		_result = rhs._result;
-		rhs._impl = 0;
+		rhs._impl = PUGIXML_NULL;
 		rhs._result = xpath_parse_result();
 	}
 
@@ -12879,7 +12879,7 @@ namespace pugi
 
 		_impl = rhs._impl;
 		_result = rhs._result;
-		rhs._impl = 0;
+		rhs._impl = PUGIXML_NULL;
 		rhs._result = xpath_parse_result();
 
 		return *this;
@@ -13043,7 +13043,7 @@ namespace pugi
 
 	PUGI__FN xpath_query::operator xpath_query::unspecified_bool_type() const
 	{
-		return _impl ? unspecified_bool_xpath_query : 0;
+		return _impl ? unspecified_bool_xpath_query : PUGIXML_NULL;
 	}
 
 	PUGI__FN bool xpath_query::operator!() const
diff --git a/tests/allocator.cpp b/tests/allocator.cpp
index 588e456..6e5c3f0 100644
--- a/tests/allocator.cpp
+++ b/tests/allocator.cpp
@@ -15,6 +15,15 @@
 #	endif
 #endif
 
+// If C++ is 2011 or higher, use 'nullptr'
+#ifndef PUGIXML_NULL
+#	if __cplusplus >= 201103
+#		define PUGIXML_NULL nullptr
+#	else
+#		define PUGIXML_NULL 0
+#	endif
+#endif
+
 // Low-level allocation functions
 #if defined(_WIN32) || defined(_WIN64)
 #	ifdef __MWERKS__
@@ -93,7 +102,6 @@ namespace
 	void* allocate_page_aligned(size_t size)
 	{
 		void* result = malloc(size + page_size);
-
 		return reinterpret_cast<void*>(align_to_page(reinterpret_cast<size_t>(result)));
 	}
 
@@ -102,7 +110,7 @@ namespace
 		size_t aligned_size = align_to_page(size);
 
 		void* ptr = allocate_page_aligned(aligned_size + page_size);
-		if (!ptr) return 0;
+		if (!ptr) return PUGIXML_NULL;
 
 		char* end = static_cast<char*>(ptr) + aligned_size;
 
@@ -147,7 +155,7 @@ const size_t memory_alignment = sizeof(double) > sizeof(void*) ? sizeof(double)
 void* memory_allocate(size_t size)
 {
 	void* result = allocate(size + memory_alignment);
-	if (!result) return 0;
+	if (!result) return PUGIXML_NULL;
 
 	memcpy(result, &size, sizeof(size_t));
 
diff --git a/tests/main.cpp b/tests/main.cpp
index 352b58b..856df1c 100644
--- a/tests/main.cpp
+++ b/tests/main.cpp
@@ -18,7 +18,7 @@
 #   include <windows.h>
 #endif
 
-test_runner* test_runner::_tests = 0;
+test_runner* test_runner::_tests = PUGIXML_NULL;
 size_t test_runner::_memory_fail_threshold = 0;
 bool test_runner::_memory_fail_triggered = false;
 jmp_buf test_runner::_failure_buffer;
@@ -36,12 +36,12 @@ static void* custom_allocate(size_t size)
 		g_memory_fail_triggered = true;
 		test_runner::_memory_fail_triggered = true;
 
-		return 0;
+		return PUGIXML_NULL;
 	}
 	else
 	{
 		void* ptr = memory_allocate(size);
-		if (!ptr) return 0;
+		if (!ptr) return PUGIXML_NULL;
 
 		g_memory_total_size += memory_size(ptr);
 		g_memory_total_count++;
@@ -183,7 +183,7 @@ int main(int, char** argv)
 	unsigned int total = 0;
 	unsigned int passed = 0;
 
-	test_runner* test = 0; // gcc3 "variable might be used uninitialized in this function" bug workaround
+	test_runner* test = PUGIXML_NULL; // gcc3 "variable might be used uninitialized in this function" bug workaround
 
 	for (test = test_runner::_tests; test; test = test->_next)
 	{
diff --git a/tests/test.cpp b/tests/test.cpp
index a97116e..4a69a85 100644
--- a/tests/test.cpp
+++ b/tests/test.cpp
@@ -164,7 +164,7 @@ xpath_node_set_tester::xpath_node_set_tester(const pugi::xpath_node_set& set, co
 
 	if (result.empty())
 	{
-		document_order = 0;
+		document_order = PUGIXML_NULL;
 		document_size = 0;
 	}
 	else
diff --git a/tests/test.hpp b/tests/test.hpp
index dd14af6..1ede950 100644
--- a/tests/test.hpp
+++ b/tests/test.hpp
@@ -138,12 +138,12 @@ struct dummy_fixture {};
 #define CHECK_XPATH_NODESET_VAR(node, query, variables) xpath_node_set_tester(pugi::xpath_query(query, variables).evaluate_node_set(node), CHECK_JOIN2(STRINGIZE(query) " does not evaluate to expected set in context " STRINGIZE(node), __FILE__, __LINE__))
 #define CHECK_XPATH_FAIL_VAR(query, variables) CHECK_TEXT(test_xpath_fail_compile(query, variables), STRINGIZE(query) " should not compile")
 
-#define CHECK_XPATH_STRING(node, query, expected) CHECK_XPATH_STRING_VAR(node, query, 0, expected)
-#define CHECK_XPATH_BOOLEAN(node, query, expected) CHECK_XPATH_BOOLEAN_VAR(node, query, 0, expected)
-#define CHECK_XPATH_NUMBER(node, query, expected) CHECK_XPATH_NUMBER_VAR(node, query, 0, expected)
-#define CHECK_XPATH_NUMBER_NAN(node, query) CHECK_XPATH_NUMBER_NAN_VAR(node, query, 0)
-#define CHECK_XPATH_NODESET(node, query) CHECK_XPATH_NODESET_VAR(node, query, 0)
-#define CHECK_XPATH_FAIL(query) CHECK_XPATH_FAIL_VAR(query, 0)
+#define CHECK_XPATH_STRING(node, query, expected) CHECK_XPATH_STRING_VAR(node, query, PUGIXML_NULL, expected)
+#define CHECK_XPATH_BOOLEAN(node, query, expected) CHECK_XPATH_BOOLEAN_VAR(node, query, PUGIXML_NULL, expected)
+#define CHECK_XPATH_NUMBER(node, query, expected) CHECK_XPATH_NUMBER_VAR(node, query, PUGIXML_NULL, expected)
+#define CHECK_XPATH_NUMBER_NAN(node, query) CHECK_XPATH_NUMBER_NAN_VAR(node, query, PUGIXML_NULL)
+#define CHECK_XPATH_NODESET(node, query) CHECK_XPATH_NODESET_VAR(node, query, PUGIXML_NULL)
+#define CHECK_XPATH_FAIL(query) CHECK_XPATH_FAIL_VAR(query, PUGIXML_NULL)
 #endif
 
 #ifdef PUGIXML_NO_EXCEPTIONS
diff --git a/tests/test_document.cpp b/tests/test_document.cpp
index 2e2904d..0d98835 100644
--- a/tests/test_document.cpp
+++ b/tests/test_document.cpp
@@ -889,7 +889,7 @@ TEST(document_parse_result_description)
 	{
 		result.status = static_cast<xml_parse_status>(i);
 
-		CHECK(result.description() != 0);
+		CHECK(result.description() != PUGIXML_NULL);
 		CHECK(result.description()[0] != 0);
 	}
 }
@@ -1098,11 +1098,11 @@ TEST(document_contents_preserve)
 {
 	file_data_t files[] =
 	{
-		{"tests/data/utftest_utf16_be_clean.xml", encoding_utf16_be, 0, 0},
-		{"tests/data/utftest_utf16_le_clean.xml", encoding_utf16_le, 0, 0},
-		{"tests/data/utftest_utf32_be_clean.xml", encoding_utf32_be, 0, 0},
-		{"tests/data/utftest_utf32_le_clean.xml", encoding_utf32_le, 0, 0},
-		{"tests/data/utftest_utf8_clean.xml", encoding_utf8, 0, 0}
+		{"tests/data/utftest_utf16_be_clean.xml", encoding_utf16_be, PUGIXML_NULL, 0},
+		{"tests/data/utftest_utf16_le_clean.xml", encoding_utf16_le, PUGIXML_NULL, 0},
+		{"tests/data/utftest_utf32_be_clean.xml", encoding_utf32_be, PUGIXML_NULL, 0},
+		{"tests/data/utftest_utf32_le_clean.xml", encoding_utf32_le, PUGIXML_NULL, 0},
+		{"tests/data/utftest_utf8_clean.xml", encoding_utf8, PUGIXML_NULL, 0}
 	};
 
 	// load files in memory
@@ -1136,8 +1136,8 @@ TEST(document_contents_preserve_latin1)
 {
 	file_data_t files[] =
 	{
-		{"tests/data/latintest_utf8.xml", encoding_utf8, 0, 0},
-		{"tests/data/latintest_latin1.xml", encoding_latin1, 0, 0}
+		{"tests/data/latintest_utf8.xml", encoding_utf8, PUGIXML_NULL, 0},
+		{"tests/data/latintest_latin1.xml", encoding_latin1, PUGIXML_NULL, 0}
 	};
 
 	// load files in memory
@@ -1239,15 +1239,15 @@ TEST(document_load_buffer_empty)
 
 		xml_document doc;
 		CHECK(doc.load_buffer(buffer, 0, parse_default, encoding).status == status_no_document_element && !doc.first_child());
-		CHECK(doc.load_buffer(0, 0, parse_default, encoding).status == status_no_document_element && !doc.first_child());
+		CHECK(doc.load_buffer(PUGIXML_NULL, 0, parse_default, encoding).status == status_no_document_element && !doc.first_child());
 
 		CHECK(doc.load_buffer_inplace(buffer, 0, parse_default, encoding).status == status_no_document_element && !doc.first_child());
-		CHECK(doc.load_buffer_inplace(0, 0, parse_default, encoding).status == status_no_document_element && !doc.first_child());
+		CHECK(doc.load_buffer_inplace(PUGIXML_NULL, 0, parse_default, encoding).status == status_no_document_element && !doc.first_child());
 
 		void* own_buffer = get_memory_allocation_function()(1);
 
 		CHECK(doc.load_buffer_inplace_own(own_buffer, 0, parse_default, encoding).status == status_no_document_element && !doc.first_child());
-		CHECK(doc.load_buffer_inplace_own(0, 0, parse_default, encoding).status == status_no_document_element && !doc.first_child());
+		CHECK(doc.load_buffer_inplace_own(PUGIXML_NULL, 0, parse_default, encoding).status == status_no_document_element && !doc.first_child());
 	}
 }
 
@@ -1275,15 +1275,15 @@ TEST(document_load_buffer_empty_fragment)
 
 		xml_document doc;
 		CHECK(doc.load_buffer(buffer, 0, parse_fragment, encoding) && !doc.first_child());
-		CHECK(doc.load_buffer(0, 0, parse_fragment, encoding) && !doc.first_child());
+		CHECK(doc.load_buffer(PUGIXML_NULL, 0, parse_fragment, encoding) && !doc.first_child());
 
 		CHECK(doc.load_buffer_inplace(buffer, 0, parse_fragment, encoding) && !doc.first_child());
-		CHECK(doc.load_buffer_inplace(0, 0, parse_fragment, encoding) && !doc.first_child());
+		CHECK(doc.load_buffer_inplace(PUGIXML_NULL, 0, parse_fragment, encoding) && !doc.first_child());
 
 		void* own_buffer = get_memory_allocation_function()(1);
 
 		CHECK(doc.load_buffer_inplace_own(own_buffer, 0, parse_fragment, encoding) && !doc.first_child());
-		CHECK(doc.load_buffer_inplace_own(0, 0, parse_fragment, encoding) && !doc.first_child());
+		CHECK(doc.load_buffer_inplace_own(PUGIXML_NULL, 0, parse_fragment, encoding) && !doc.first_child());
 	}
 }
 
@@ -1291,11 +1291,11 @@ TEST(document_load_buffer_null)
 {
 	xml_document doc;
 
-	CHECK(doc.load_buffer(0, 12).status == status_io_error && !doc.first_child());
-	CHECK(doc.load_buffer(0, 12, parse_fragment).status == status_io_error && !doc.first_child());
+	CHECK(doc.load_buffer(PUGIXML_NULL, 12).status == status_io_error && !doc.first_child());
+	CHECK(doc.load_buffer(PUGIXML_NULL, 12, parse_fragment).status == status_io_error && !doc.first_child());
 
-	CHECK(doc.load_buffer_inplace(0, 12).status == status_io_error && !doc.first_child());
-	CHECK(doc.load_buffer_inplace_own(0, 12).status == status_io_error && !doc.first_child());
+	CHECK(doc.load_buffer_inplace(PUGIXML_NULL, 12).status == status_io_error && !doc.first_child());
+	CHECK(doc.load_buffer_inplace_own(PUGIXML_NULL, 12).status == status_io_error && !doc.first_child());
 }
 
 TEST(document_progressive_truncation)
@@ -1350,7 +1350,7 @@ TEST(document_load_buffer_short)
 	CHECK(doc.load_buffer(data + 2, 2).status == status_no_document_element);
 	CHECK(doc.load_buffer(data + 3, 1).status == status_no_document_element);
 	CHECK(doc.load_buffer(data + 4, 0).status == status_no_document_element);
-	CHECK(doc.load_buffer(0, 0).status == status_no_document_element);
+	CHECK(doc.load_buffer(PUGIXML_NULL, 0).status == status_no_document_element);
 
 	delete[] data;
 }
@@ -1367,7 +1367,7 @@ TEST(document_load_buffer_short_fragment)
 	CHECK(doc.load_buffer(data + 2, 2, parse_fragment) && test_string_equal(doc.text().get(), STR("cd")));
 	CHECK(doc.load_buffer(data + 3, 1, parse_fragment) && test_string_equal(doc.text().get(), STR("d")));
 	CHECK(doc.load_buffer(data + 4, 0, parse_fragment) && !doc.first_child());
-	CHECK(doc.load_buffer(0, 0, parse_fragment) && !doc.first_child());
+	CHECK(doc.load_buffer(PUGIXML_NULL, 0, parse_fragment) && !doc.first_child());
 
 	delete[] data;
 }
@@ -1384,7 +1384,7 @@ TEST(document_load_buffer_inplace_short)
 	CHECK(doc.load_buffer_inplace(data + 2, 2).status == status_no_document_element);
 	CHECK(doc.load_buffer_inplace(data + 3, 1).status == status_no_document_element);
 	CHECK(doc.load_buffer_inplace(data + 4, 0).status == status_no_document_element);
-	CHECK(doc.load_buffer_inplace(0, 0).status == status_no_document_element);
+	CHECK(doc.load_buffer_inplace(PUGIXML_NULL, 0).status == status_no_document_element);
 
 	delete[] data;
 }
@@ -1597,12 +1597,12 @@ TEST(document_convert_out_of_memory)
 {
 	file_data_t files[] =
 	{
-		{"tests/data/utftest_utf16_be_clean.xml", encoding_utf16_be, 0, 0},
-		{"tests/data/utftest_utf16_le_clean.xml", encoding_utf16_le, 0, 0},
-		{"tests/data/utftest_utf32_be_clean.xml", encoding_utf32_be, 0, 0},
-		{"tests/data/utftest_utf32_le_clean.xml", encoding_utf32_le, 0, 0},
-		{"tests/data/utftest_utf8_clean.xml", encoding_utf8, 0, 0},
-		{"tests/data/latintest_latin1.xml", encoding_latin1, 0, 0}
+		{"tests/data/utftest_utf16_be_clean.xml", encoding_utf16_be, PUGIXML_NULL, 0},
+		{"tests/data/utftest_utf16_le_clean.xml", encoding_utf16_le, PUGIXML_NULL, 0},
+		{"tests/data/utftest_utf32_be_clean.xml", encoding_utf32_be, PUGIXML_NULL, 0},
+		{"tests/data/utftest_utf32_le_clean.xml", encoding_utf32_le, PUGIXML_NULL, 0},
+		{"tests/data/utftest_utf8_clean.xml", encoding_utf8, PUGIXML_NULL, 0},
+		{"tests/data/latintest_latin1.xml", encoding_latin1, PUGIXML_NULL, 0}
 	};
 
 	// load files in memory
diff --git a/tests/test_dom_modify.cpp b/tests/test_dom_modify.cpp
index 3451f19..f28e058 100644
--- a/tests/test_dom_modify.cpp
+++ b/tests/test_dom_modify.cpp
@@ -1345,8 +1345,8 @@ TEST_XML(dom_node_append_buffer_empty, "<node />")
 	CHECK(node.append_buffer("", 0).status == status_no_document_element);
 	CHECK(node.append_buffer("", 0, parse_fragment).status == status_ok);
 
-	CHECK(node.append_buffer(0, 0).status == status_no_document_element);
-	CHECK(node.append_buffer(0, 0, parse_fragment).status == status_ok);
+	CHECK(node.append_buffer(PUGIXML_NULL, 0).status == status_no_document_element);
+	CHECK(node.append_buffer(PUGIXML_NULL, 0, parse_fragment).status == status_ok);
 
 	CHECK_NODE(doc, STR("<node/>"));
 }
diff --git a/tests/test_dom_traverse.cpp b/tests/test_dom_traverse.cpp
index 0c1e3af..d7af87b 100644
--- a/tests/test_dom_traverse.cpp
+++ b/tests/test_dom_traverse.cpp
@@ -981,14 +981,14 @@ TEST_XML(dom_internal_object, "<node attr='value'>value</node>")
 	xml_attribute attr = node.first_attribute();
 	xml_node value = node.first_child();
 
-	CHECK(xml_node().internal_object() == 0);
-	CHECK(xml_attribute().internal_object() == 0);
+	CHECK(xml_node().internal_object() == PUGIXML_NULL);
+	CHECK(xml_attribute().internal_object() == PUGIXML_NULL);
 
-    CHECK(node.internal_object() != 0);
-    CHECK(value.internal_object() != 0);
+    CHECK(node.internal_object() != PUGIXML_NULL);
+    CHECK(value.internal_object() != PUGIXML_NULL);
     CHECK(node.internal_object() != value.internal_object());
 
-    CHECK(attr.internal_object() != 0);
+    CHECK(attr.internal_object() != PUGIXML_NULL);
 
     xml_node node_copy = node;
     CHECK(node_copy.internal_object() == node.internal_object());
@@ -1100,24 +1100,24 @@ TEST_XML(dom_unspecified_bool_coverage, "<node attr='value'>text</node>")
 	xml_node node = doc.first_child();
 
 	CHECK(node);
-	static_cast<void (*)(xml_node***)>(node)(0);
+	static_cast<void (*)(xml_node***)>(node)(PUGIXML_NULL);
 
 	CHECK(node.first_attribute());
-	static_cast<void (*)(xml_attribute***)>(node.first_attribute())(0);
+	static_cast<void (*)(xml_attribute***)>(node.first_attribute())(PUGIXML_NULL);
 
 	CHECK(node.text());
-	static_cast<void (*)(xml_text***)>(node.text())(0);
+	static_cast<void (*)(xml_text***)>(node.text())(PUGIXML_NULL);
 
 #ifndef PUGIXML_NO_XPATH
 	xpath_query q(STR("/node"));
 
 	CHECK(q);
-	static_cast<void (*)(xpath_query***)>(q)(0);
+	static_cast<void (*)(xpath_query***)>(q)(PUGIXML_NULL);
 
 	xpath_node qn = q.evaluate_node(doc);
 
 	CHECK(qn);
-	static_cast<void (*)(xpath_node***)>(qn)(0);
+	static_cast<void (*)(xpath_node***)>(qn)(PUGIXML_NULL);
 #endif
 }
 
diff --git a/tests/test_xpath.cpp b/tests/test_xpath.cpp
index 0fbe392..6e18af5 100644
--- a/tests/test_xpath.cpp
+++ b/tests/test_xpath.cpp
@@ -416,7 +416,7 @@ TEST_XML(xpath_out_of_memory_evaluate, "<n/>")
 	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(doc).empty()));
 #endif
 
-	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(0, 0, doc) == 1));
+	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(PUGIXML_NULL, 0, doc) == 1));
 	CHECK_ALLOC_FAIL(CHECK(q.evaluate_node(doc) == xpath_node()));
 	CHECK_ALLOC_FAIL(CHECK(q.evaluate_node_set(doc).empty()));
 }
@@ -432,7 +432,7 @@ TEST(xpath_out_of_memory_evaluate_concat)
 
 	xpath_query q(query.c_str());
 
-	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(0, 0, xml_node()) == 1));
+	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(PUGIXML_NULL, 0, xml_node()) == 1));
 }
 
 TEST(xpath_out_of_memory_evaluate_concat_list)
@@ -448,7 +448,7 @@ TEST(xpath_out_of_memory_evaluate_concat_list)
 
 	test_runner::_memory_fail_threshold = 1;
 
-	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(0, 0, xml_node()) == 1));
+	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(PUGIXML_NULL, 0, xml_node()) == 1));
 }
 
 TEST(xpath_out_of_memory_evaluate_substring)
@@ -462,7 +462,7 @@ TEST(xpath_out_of_memory_evaluate_substring)
 
 	xpath_query q(query.c_str());
 
-	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(0, 0, xml_node()) == 1));
+	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(PUGIXML_NULL, 0, xml_node()) == 1));
 }
 
 TEST_XML(xpath_out_of_memory_evaluate_union, "<node />")
@@ -516,7 +516,7 @@ TEST_XML(xpath_out_of_memory_evaluate_normalize_space_0, "<node> a b c d e f g h
 
 	xpath_query q(STR("concat(normalize-space(), normalize-space(), normalize-space(), normalize-space(), normalize-space(), normalize-space(), normalize-space(), normalize-space())"));
 
-	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(0, 0, doc.first_child()) == 1));
+	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(PUGIXML_NULL, 0, doc.first_child()) == 1));
 }
 
 TEST_XML(xpath_out_of_memory_evaluate_normalize_space_1, "<node> a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z </node>")
@@ -525,7 +525,7 @@ TEST_XML(xpath_out_of_memory_evaluate_normalize_space_1, "<node> a b c d e f g h
 
 	xpath_query q(STR("concat(normalize-space(node), normalize-space(node), normalize-space(node), normalize-space(node), normalize-space(node), normalize-space(node), normalize-space(node), normalize-space(node))"));
 
-	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(0, 0, doc) == 1));
+	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(PUGIXML_NULL, 0, doc) == 1));
 }
 
 TEST_XML(xpath_out_of_memory_evaluate_translate, "<node> a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z </node>")
@@ -534,7 +534,7 @@ TEST_XML(xpath_out_of_memory_evaluate_translate, "<node> a b c d e f g h i j k l
 
 	xpath_query q(STR("concat(translate(node, 'a', '\xe9'), translate(node, 'a', '\xe9'), translate(node, 'a', '\xe9'), translate(node, 'a', '\xe9'), translate(node, 'a', '\xe9'), translate(node, 'a', '\xe9'), translate(node, 'a', '\xe9'), translate(node, 'a', '\xe9'))"));
 
-	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(0, 0, doc) == 1));
+	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(PUGIXML_NULL, 0, doc) == 1));
 }
 
 TEST_XML(xpath_out_of_memory_evaluate_translate_table, "<node> a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y z </node>")
@@ -543,7 +543,7 @@ TEST_XML(xpath_out_of_memory_evaluate_translate_table, "<node> a b c d e f g h i
 
 	xpath_query q(STR("concat(translate(node, 'a', 'A'), translate(node, 'a', 'A'), translate(node, 'a', 'A'), translate(node, 'a', 'A'), translate(node, 'a', 'A'), translate(node, 'a', 'A'), translate(node, 'a', 'A'), translate(node, 'a', 'A'))"));
 
-	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(0, 0, doc) == 1));
+	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(PUGIXML_NULL, 0, doc) == 1));
 }
 
 TEST(xpath_out_of_memory_evaluate_string_append)
@@ -563,7 +563,7 @@ TEST(xpath_out_of_memory_evaluate_string_append)
 	xpath_query q(STR("string(n)"));
 	CHECK(q);
 
-	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(0, 0, doc) == 1));
+	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(PUGIXML_NULL, 0, doc) == 1));
 }
 
 TEST(xpath_out_of_memory_evaluate_number_to_string)
@@ -575,7 +575,7 @@ TEST(xpath_out_of_memory_evaluate_number_to_string)
 
 	xpath_query q(STR("concat($x, $x, $x, $x, $x, $x, $x, $x, $x, $x, $x, $x, $x, $x, $x, $x, $x)"), &vars);
 
-	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(0, 0, xml_node()) == 1));
+	CHECK_ALLOC_FAIL(CHECK(q.evaluate_string(PUGIXML_NULL, 0, xml_node()) == 1));
 }
 
 TEST(xpath_memory_concat_massive)
@@ -587,7 +587,7 @@ TEST(xpath_memory_concat_massive)
 		node.append_child(STR("c")).text().set(i % 10);
 
 	xpath_query q(STR("/"));
-	size_t size = q.evaluate_string(0, 0, node);
+	size_t size = q.evaluate_string(PUGIXML_NULL, 0, node);
 
 	CHECK(size == 5001);
 }
diff --git a/tests/test_xpath_api.cpp b/tests/test_xpath_api.cpp
index 8687e35..b426e3d 100644
--- a/tests/test_xpath_api.cpp
+++ b/tests/test_xpath_api.cpp
@@ -198,7 +198,7 @@ TEST_XML(xpath_api_evaluate_fail, "<node attr='3'/>")
 	CHECK(q.evaluate_boolean(doc) == false);
 	CHECK_DOUBLE_NAN(q.evaluate_number(doc));
 
-	CHECK(q.evaluate_string(0, 0, doc) == 1); // null terminator
+	CHECK(q.evaluate_string(PUGIXML_NULL, 0, doc) == 1); // null terminator
 
 #ifndef PUGIXML_NO_STL
 	CHECK(q.evaluate_string(doc).empty());
@@ -277,7 +277,7 @@ TEST(xpath_api_evaluate_string)
 	// test for empty buffer
 	std::basic_string<char_t> s5 = base;
 	CHECK(q.evaluate_string(&s5[0], 0, xml_node()) == 11 && memcmp(&s5[0], STR("xxxxxxxxxxxxxxxx"), 16 * sizeof(char_t)) == 0);
-	CHECK(q.evaluate_string(0, 0, xml_node()) == 11);
+	CHECK(q.evaluate_string(PUGIXML_NULL, 0, xml_node()) == 11);
 }
 
 TEST(xpath_api_return_type)
@@ -315,7 +315,7 @@ TEST(xpath_api_query_result)
 	xpath_query q(STR("node"));
 
 	CHECK(q.result());
-	CHECK(q.result().error == 0);
+	CHECK(q.result().error == PUGIXML_NULL);
 	CHECK(q.result().offset == 0);
 	CHECK(strcmp(q.result().description(), "No error") == 0);
 }
@@ -337,7 +337,7 @@ TEST(xpath_api_query_result_fail)
 		xpath_parse_result result = q.result();
 
 		CHECK(!result);
-		CHECK(result.error != 0 && result.error[0] != 0);
+		CHECK(result.error != PUGIXML_NULL && result.error[0] != 0);
 		CHECK(result.description() == result.error);
 		CHECK(result.offset == 13);
 
diff --git a/tests/test_xpath_parse.cpp b/tests/test_xpath_parse.cpp
index bfa59ff..e30ea4c 100644
--- a/tests/test_xpath_parse.cpp
+++ b/tests/test_xpath_parse.cpp
@@ -332,7 +332,7 @@ TEST(xpath_parse_result_default)
 	xpath_parse_result result;
 
 	CHECK(!result);
-	CHECK(result.error != 0);
+	CHECK(result.error != PUGIXML_NULL);
 	CHECK(result.offset == 0);
 }
 
diff --git a/tests/test_xpath_variables.cpp b/tests/test_xpath_variables.cpp
index 1a1fc19..09388fc 100644
--- a/tests/test_xpath_variables.cpp
+++ b/tests/test_xpath_variables.cpp
@@ -135,15 +135,15 @@ TEST(xpath_variables_set_operations)
 
 	CHECK(set.add(STR("var1"), xpath_type_number) == v1);
 	CHECK(set.add(STR("var2"), xpath_type_string) == v2);
-	CHECK(set.add(STR("var2"), xpath_type_node_set) == 0);
+	CHECK(set.add(STR("var2"), xpath_type_node_set) == PUGIXML_NULL);
 
 	CHECK(set.get(STR("var1")) == v1);
 	CHECK(set.get(STR("var2")) == v2);
-	CHECK(set.get(STR("var")) == 0);
-	CHECK(set.get(STR("var11")) == 0);
+	CHECK(set.get(STR("var")) == PUGIXML_NULL);
+	CHECK(set.get(STR("var11")) == PUGIXML_NULL);
 
 	CHECK(static_cast<const xpath_variable_set&>(set).get(STR("var1")) == v1);
-	CHECK(static_cast<const xpath_variable_set&>(set).get(STR("var3")) == 0);
+	CHECK(static_cast<const xpath_variable_set&>(set).get(STR("var3")) == PUGIXML_NULL);
 }
 
 TEST_XML(xpath_variables_set_operations_set, "<node/>")
@@ -179,7 +179,7 @@ TEST(xpath_variables_set_out_of_memory)
 
 	xpath_variable_set set;
 
-	xpath_variable* var = 0;
+	xpath_variable* var = PUGIXML_NULL;
 	CHECK_ALLOC_FAIL(var = set.add(STR("target"), xpath_type_number));
 	CHECK(!var);
 }