diff --git a/include/rapidjson/document.h b/include/rapidjson/document.h
index e3e20df..6d4c1a4 100644
--- a/include/rapidjson/document.h
+++ b/include/rapidjson/document.h
@@ -317,6 +317,6 @@ struct GenericStringRef {
     GenericStringRef(const GenericStringRef& rhs) : s(rhs.s), length(rhs.length) {}
 
-    GenericStringRef& operator=(const GenericStringRef& rhs) { s = rhs.s; length = rhs.length; }
+    GenericStringRef& operator=(const GenericStringRef& rhs) /* = delete */;
 
     //! implicit conversion to plain CharType pointer
     operator const Ch *() const { return s; }