diff --git a/src/pugixml.hpp b/src/pugixml.hpp
index cdd24b6..f70252e 100644
--- a/src/pugixml.hpp
+++ b/src/pugixml.hpp
@@ -945,7 +945,7 @@ namespace pugi
 		
 		// Non-copyable semantics
 		xml_document(const xml_document&);
-		const xml_document& operator=(const xml_document&);
+		xml_document& operator=(const xml_document&);
 
 		void create();
 		void destroy();