diff --git a/demos/blockfactory/blocks.js b/demos/blockfactory/blocks.js
index 8818a74b9..8927e6453 100644
--- a/demos/blockfactory/blocks.js
+++ b/demos/blockfactory/blocks.js
@@ -336,8 +336,8 @@ Blockly.Blocks['field_dropdown'] = {
     this.updateShape_();
     this.setPreviousStatement(true, 'Field');
     this.setNextStatement(true, 'Field');
-    this.setMutator(new Blockly.icons.MutatorIcon(['field_dropdown_option_text',
-                                         'field_dropdown_option_image']));
+    this.setMutator(new Blockly.icons.MutatorIcon(
+        ['field_dropdown_option_text', 'field_dropdown_option_image'], this));
     this.setColour(160);
     this.setTooltip('Dropdown menu with a list of options.');
     this.setHelpUrl('https://www.youtube.com/watch?v=s2_xaEvcVI0#t=386');
@@ -611,7 +611,7 @@ Blockly.Blocks['type_group'] = {
     this.typeCount_ = 2;
     this.updateShape_();
     this.setOutput(true, 'Type');
-    this.setMutator(new Blockly.icons.MutatorIcon(['type_group_item']));
+    this.setMutator(new Blockly.icons.MutatorIcon(['type_group_item'], this));
     this.setColour(230);
     this.setTooltip('Allows more than one type to be accepted.');
     this.setHelpUrl('https://www.youtube.com/watch?v=s2_xaEvcVI0#t=677');