diff --git a/core/options.js b/core/options.js
index 489a0dfb3..4262125ac 100644
--- a/core/options.js
+++ b/core/options.js
@@ -363,3 +363,19 @@ Blockly.Options.parseThemeOptions_ = function(options) {
   return Blockly.Theme.defineTheme(theme.name ||
       ('builtin' + Blockly.utils.IdGenerator.getNextUniqueId()), theme);
 };
+
+/**
+ * Parse the provided toolbox tree into a consistent DOM format.
+ * @param {?Node|?string} toolboxDef DOM tree of blocks, or text representation
+ *    of same.
+ * @return {?Node} DOM tree of blocks, or null.
+ * @deprecated Use Blockly.utils.toolbox.parseToolboxTree. (2020 September 28)
+ */
+Blockly.Options.parseToolboxTree = function(toolboxDef) {
+  Blockly.utils.deprecation.warn(
+      'Blockly.Options.parseToolboxTree',
+      'September 2020',
+      'September 2021',
+      'Blockly.utils.toolbox.parseToolboxTree');
+  return Blockly.utils.toolbox.parseToolboxTree(toolboxDef);
+};
diff --git a/core/toolbox/toolbox_item.js b/core/toolbox/toolbox_item.js
index 550b47aea..31ef3b611 100644
--- a/core/toolbox/toolbox_item.js
+++ b/core/toolbox/toolbox_item.js
@@ -34,7 +34,7 @@ Blockly.ToolboxItem = function(toolboxItemDef, toolbox, opt_parent) {
    * @type {string}
    * @protected
    */
-  this.id_ = toolboxItemDef['id'] || Blockly.utils.IdGenerator.getNextUniqueId();
+  this.id_ = toolboxItemDef['toolboxitemid'] || Blockly.utils.IdGenerator.getNextUniqueId();
 
   /**
    * The parent of the category.
diff --git a/demos/blockfactory/workspacefactory/wfactory_controller.js b/demos/blockfactory/workspacefactory/wfactory_controller.js
index cfecbbbc4..6d243ca15 100644
--- a/demos/blockfactory/workspacefactory/wfactory_controller.js
+++ b/demos/blockfactory/workspacefactory/wfactory_controller.js
@@ -398,7 +398,7 @@ WorkspaceFactoryController.prototype.updatePreview = function() {
   // Only update the toolbox if not in read only mode.
   if (!this.model.options['readOnly']) {
     // Get toolbox XML.
-    var tree = Blockly.Options.parseToolboxTree(
+    var tree = Blockly.utils.toolbox.parseToolboxTree(
         this.generator.generateToolboxXml());
 
     // No categories, creates a simple flyout.
@@ -1084,7 +1084,7 @@ WorkspaceFactoryController.prototype.setStandardOptionsAndUpdate = function() {
 WorkspaceFactoryController.prototype.generateNewOptions = function() {
   this.model.setOptions(this.readOptions_());
 
-  this.reinjectPreview(Blockly.Options.parseToolboxTree(
+  this.reinjectPreview(Blockly.utils.toolbox.parseToolboxTree(
       this.generator.generateToolboxXml()));
 };
 
diff --git a/tests/mocha/index.html b/tests/mocha/index.html
index 08a7fb642..d144f4865 100644
--- a/tests/mocha/index.html
+++ b/tests/mocha/index.html
@@ -146,10 +146,10 @@
       <category name="Second">
         <block type="stack_block"></block>
       </category>
-      <sep id="separator" gap="-1"></sep>
+      <sep toolboxitemid="separator" gap="-1"></sep>
       <category name="Variables" custom="VARIABLE"></category>
       <category name="NestedCategory" >
-        <category id="nestedCategory" name="NestedItemOne"></category>
+        <category toolboxitemid="nestedCategory" name="NestedItemOne"></category>
       </category>
       <category name="lastItem"></category>
     </xml>