diff --git a/src/pugixml.cpp b/src/pugixml.cpp
index 950d3ab..ca10ba9 100644
--- a/src/pugixml.cpp
+++ b/src/pugixml.cpp
@@ -2345,7 +2345,8 @@ PUGI__NS_BEGIN
 		size_t target_length = strlength(target);
 
 		// always reuse document buffer memory if possible
-		if ((header & header_mask) == 0) return target_length >= length;
+		if ((header & header_mask) == 0) 
+			return target_length >= length;
 
 		// reuse heap memory if waste is not too great
 		const size_t reuse_threshold = 32;
@@ -2367,6 +2368,9 @@ PUGI__NS_BEGIN
 			dest = source_length == 0 ? 0 : const_cast<char_t*>(source);
 			header &= ~header_mask;
 
+			// since strcpy_insitu can reuse document buffer memory we need to mark both dest as shared
+			header |= xml_memory_page_contents_shared_mask;
+
 			return true;
 		}
 		else if (dest && strcpy_insitu_allow(source_length, header, header_mask, dest))