diff --git a/src/stc/scintilla/src/Document.h b/src/stc/scintilla/src/Document.h
index c0a0bb8084..3811f2567a 100644
--- a/src/stc/scintilla/src/Document.h
+++ b/src/stc/scintilla/src/Document.h
@@ -211,6 +211,9 @@ public:
 		bool operator==(const WatcherWithUserData &other) const {
 			return (watcher == other.watcher) && (userData == other.userData);
 		}
+		bool operator!=(const WatcherWithUserData &other) const {
+			return !((watcher == other.watcher) && (userData == other.userData));
+		}
 	};
 
 private: