diff --git a/lib/javascript-static.js b/lib/javascript-static.js
index 71208e96663..4930b036e50 100644
--- a/lib/javascript-static.js
+++ b/lib/javascript-static.js
@@ -1569,6 +1569,7 @@ blocks.dock = {
             return false;
         }
         this.items[uid].remove();
+        delete this.items[uid];
         this.fire('dock:itemremoved', uid);
         this.count--;
         if (this.count===0) {
@@ -1588,7 +1589,7 @@ blocks.dock = {
     remove_all:function() {
         for (var i in this.items) {
             this.items[i].remove();
-            this.items[i] = null;
+            delete this.items[i];
         }
         Y.fire('dock:toberemoved');
         this.items = [];