diff --git a/lib/ace/test/mockrenderer.js b/lib/ace/test/mockrenderer.js
index ae04eed2..b542fa80 100644
--- a/lib/ace/test/mockrenderer.js
+++ b/lib/ace/test/mockrenderer.js
@@ -47,6 +47,8 @@ var MockRenderer = exports.MockRenderer = function(visibleRowCount) {
     };
 
     this.isMockRenderer = true;
+    
+    this.$gutter = {};
 };