diff --git a/lib/ace/test/mockrenderer.js b/lib/ace/test/mockrenderer.js
index 2645f5e9..ade251d5 100644
--- a/lib/ace/test/mockrenderer.js
+++ b/lib/ace/test/mockrenderer.js
@@ -81,6 +81,12 @@ MockRenderer.prototype.getTextAreaContainer = function() {
     return this.container;
 };
 
+MockRenderer.prototype.addGutterDecoration = function() {
+};
+
+MockRenderer.prototype.removeGutterDecoration = function() {
+};
+
 MockRenderer.prototype.moveTextAreaToCursor = function() {
 };