diff --git a/core/mutator.js b/core/mutator.js
index 313e3f101..540178d05 100644
--- a/core/mutator.js
+++ b/core/mutator.js
@@ -386,13 +386,6 @@ Blockly.Mutator.prototype.workspaceChanged_ = function(e) {
     if (oldMutation != newMutation) {
       Blockly.Events.fire(new Blockly.Events.BlockChange(
           block, 'mutation', null, oldMutation, newMutation));
-      // Ensure that any bump is part of this mutation's event group.
-      var group = Blockly.Events.getGroup();
-      setTimeout(function() {
-        Blockly.Events.setGroup(group);
-        block.bumpNeighbours();
-        Blockly.Events.setGroup(false);
-      }, Blockly.BUMP_DELAY);
     }
 
     // Don't update the bubble until the drag has ended, to avoid moving blocks