diff --git a/docs/samples/save_custom_writer.cpp b/docs/samples/save_custom_writer.cpp
index 9e9ee34..fe08b72 100644
--- a/docs/samples/save_custom_writer.cpp
+++ b/docs/samples/save_custom_writer.cpp
@@ -11,7 +11,7 @@ struct xml_string_writer: pugi::xml_writer
 
     virtual void write(const void* data, size_t size)
     {
-        result += std::string(static_cast<const char*>(data), size);
+        result.append(static_cast<const char*>(data), size);
     }
 };
 //]
diff --git a/tests/test_write.cpp b/tests/test_write.cpp
index ca230c3..da83745 100644
--- a/tests/test_write.cpp
+++ b/tests/test_write.cpp
@@ -171,7 +171,7 @@ struct test_writer: xml_writer
 	virtual void write(const void* data, size_t size)
 	{
 		CHECK(size % sizeof(pugi::char_t) == 0);
-		contents += std::basic_string<pugi::char_t>(static_cast<const pugi::char_t*>(data), static_cast<const pugi::char_t*>(data) + size / sizeof(pugi::char_t));
+		contents.append(static_cast<const pugi::char_t*>(data), size / sizeof(pugi::char_t));
 	}
 };
 
diff --git a/tests/writer_string.cpp b/tests/writer_string.cpp
index a09678b..661c792 100644
--- a/tests/writer_string.cpp
+++ b/tests/writer_string.cpp
@@ -15,7 +15,7 @@ static bool test_narrow(const std::string& result, const char* expected, size_t
 
 void xml_writer_string::write(const void* data, size_t size)
 {
-	contents += std::string(static_cast<const char*>(data), size);
+	contents.append(static_cast<const char*>(data), size);
 }
 
 std::string xml_writer_string::as_narrow() const