diff --git a/src/static/js/ace2_inner.js b/src/static/js/ace2_inner.js
index 067b546b9..0d54d7251 100644
--- a/src/static/js/ace2_inner.js
+++ b/src/static/js/ace2_inner.js
@@ -5180,7 +5180,6 @@ function Ace2Inner(){
       {
         if(n > lineNumbersShown) //all updated, break
         break;
-
         var h = (b.clientHeight || b.offsetHeight);
         if (b.nextSibling)
         {
@@ -5215,17 +5214,23 @@ function Ace2Inner(){
         var n = lineNumbersShown;
         var div = odoc.createElement("DIV");	
         //calculate height for new line number
-        var h = (b.clientHeight || b.offsetHeight);
+        if(b){
+          var h = (b.clientHeight || b.offsetHeight);
         
-        if (b.nextSibling)
-          h = b.nextSibling.offsetTop - b.offsetTop;
+          if (b.nextSibling){
+            h = b.nextSibling.offsetTop - b.offsetTop;
+          }
+        }
         
-        if(h) // apply style to div
+        if(h){ // apply style to div
           div.style.height = h +"px";
-			
+	}
+		
         div.appendChild(odoc.createTextNode(String(n)));
         fragment.appendChild(div);
-        b = b.nextSibling;
+        if(b){
+          b = b.nextSibling;
+        }
       }
       
       container.appendChild(fragment);