diff --git a/include/rapidjson/document.h b/include/rapidjson/document.h
index 44cf532..33c97f4 100644
--- a/include/rapidjson/document.h
+++ b/include/rapidjson/document.h
@@ -270,10 +270,12 @@ struct GenericStringRef {
 	//! implicit conversion to plain CharType pointer
 	operator const Ch *() const { return s; }
 
-	const Ch* s; //!< plain CharType pointer
+	const Ch* const s; //!< plain CharType pointer
 	const SizeType length; //!< length of the string (excluding the trailing NULL terminator)
 
 private:
+	//! Disallow copy-assignment
+	GenericStringRef operator=(const GenericStringRef&);
 	//! Disallow construction from non-const array
 	template<SizeType N>
 	GenericStringRef(CharType (&str)[N]) /* = delete */;