diff --git a/core/toolbox/separator.js b/core/toolbox/separator.js
index 664fa4584..dbf30f4f0 100644
--- a/core/toolbox/separator.js
+++ b/core/toolbox/separator.js
@@ -17,7 +17,6 @@ goog.module.declareLegacyNamespace();
 const Css = goog.require('Blockly.Css');
 /* eslint-disable-next-line no-unused-vars */
 const IToolbox = goog.requireType('Blockly.IToolbox');
-const IToolboxItem = goog.require('Blockly.IToolboxItem');
 const ToolboxItem = goog.require('Blockly.ToolboxItem');
 const dom = goog.require('Blockly.utils.dom');
 const object = goog.require('Blockly.utils.object');
@@ -34,7 +33,6 @@ const toolbox = goog.requireType('Blockly.utils.toolbox');
  * @param {!IToolbox} toolbox The parent toolbox for the separator.
  * @constructor
  * @extends {ToolboxItem}
- * @implements {IToolboxItem}
  */
 const ToolboxSeparator = function(separatorDef, toolbox) {
   ToolboxSeparator.superClass_.constructor.call(this, separatorDef, toolbox);
diff --git a/tests/deps.js b/tests/deps.js
index 1e3476539..69bb647ad 100644
--- a/tests/deps.js
+++ b/tests/deps.js
@@ -170,7 +170,7 @@ goog.addDependency('../../core/theme/zelos.js', ['Blockly.Themes.Zelos'], ['Bloc
 goog.addDependency('../../core/theme_manager.js', ['Blockly.ThemeManager'], ['Blockly.utils.dom'], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../core/toolbox/category.js', ['Blockly.ToolboxCategory'], ['Blockly.ISelectableToolboxItem', 'Blockly.ToolboxItem', 'Blockly.registry', 'Blockly.utils', 'Blockly.utils.aria', 'Blockly.utils.dom', 'Blockly.utils.object', 'Blockly.utils.toolbox'], {'lang': 'es5'});
 goog.addDependency('../../core/toolbox/collapsible_category.js', ['Blockly.CollapsibleToolboxCategory'], ['Blockly.ICollapsibleToolboxItem', 'Blockly.ToolboxCategory', 'Blockly.ToolboxSeparator', 'Blockly.registry', 'Blockly.utils.aria', 'Blockly.utils.dom', 'Blockly.utils.object', 'Blockly.utils.toolbox'], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../core/toolbox/separator.js', ['Blockly.ToolboxSeparator'], ['Blockly.Css', 'Blockly.IToolboxItem', 'Blockly.ToolboxItem', 'Blockly.registry', 'Blockly.utils.dom', 'Blockly.utils.object'], {'lang': 'es6', 'module': 'goog'});
+goog.addDependency('../../core/toolbox/separator.js', ['Blockly.ToolboxSeparator'], ['Blockly.Css', 'Blockly.ToolboxItem', 'Blockly.registry', 'Blockly.utils.dom', 'Blockly.utils.object'], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../core/toolbox/toolbox.js', ['Blockly.Toolbox'], ['Blockly.BlockSvg', 'Blockly.CollapsibleToolboxCategory', 'Blockly.ComponentManager', 'Blockly.Css', 'Blockly.DeleteArea', 'Blockly.Events', 'Blockly.Events.ToolboxItemSelect', 'Blockly.IAutoHideable', 'Blockly.IKeyboardAccessible', 'Blockly.IStyleable', 'Blockly.IToolbox', 'Blockly.Options', 'Blockly.Touch', 'Blockly.browserEvents', 'Blockly.constants', 'Blockly.registry', 'Blockly.utils', 'Blockly.utils.Rect', 'Blockly.utils.aria', 'Blockly.utils.dom', 'Blockly.utils.toolbox'], {'lang': 'es5'});
 goog.addDependency('../../core/toolbox/toolbox_item.js', ['Blockly.ToolboxItem'], ['Blockly.IToolboxItem', 'Blockly.utils.IdGenerator'], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../core/tooltip.js', ['Blockly.Tooltip'], ['Blockly.browserEvents', 'Blockly.utils.string']);