diff --git a/static/js/Editor.js b/static/js/Editor.js
index c992f8f..91be4ec 100644
--- a/static/js/Editor.js
+++ b/static/js/Editor.js
@@ -872,7 +872,7 @@ Editor.prototype.mouse_hovered = function ( event ) {
 
 Editor.prototype.mouse_hover_timeout = function ( hover_target ) {
   // if the mouse is hovering over the same target that it was when the timer started
-  if ( hover_target == this.hover_target )
+  if ( hover_target == this.hover_target && this.iframe )
     signal( this, "mouse_hovered", hover_target );
 }