diff --git a/lib/ace/document.js b/lib/ace/document.js
index ee0ce11f..bfd80de9 100644
--- a/lib/ace/document.js
+++ b/lib/ace/document.js
@@ -173,7 +173,7 @@ var Document = function(text) {
     };
 
     this.insert = function(position, text) {
-        if (text.length == 0)
+        if (!text || text.length === 0)
             return position;
 
         position = this.$clipPosition(position);