diff --git a/core/blocks.js b/core/blocks.js
index 5f0d96b21..fadc62959 100644
--- a/core/blocks.js
+++ b/core/blocks.js
@@ -14,10 +14,13 @@
  * A mapping of block type names to block prototype objects.
  * @name Blockly.Blocks
  */
-goog.provide('Blockly.Blocks');
+goog.module('Blockly.Blocks');
+goog.module.declareLegacyNamespace();
 
 /**
  * A mapping of block type names to block prototype objects.
  * @type {!Object<string,Object>}
  */
-Blockly.Blocks = Object.create(null);
+const Blocks = Object.create(null);
+
+exports = Blocks;
diff --git a/tests/deps.js b/tests/deps.js
index d1a516942..89bb3d512 100644
--- a/tests/deps.js
+++ b/tests/deps.js
@@ -13,7 +13,7 @@ goog.addDependency('../../core/block_drag_surface.js', ['Blockly.BlockDragSurfac
 goog.addDependency('../../core/block_dragger.js', ['Blockly.BlockDragger'], ['Blockly.Events', 'Blockly.Events.BlockDrag', 'Blockly.Events.BlockMove', 'Blockly.IBlockDragger', 'Blockly.InsertionMarkerManager', 'Blockly.blockAnimations', 'Blockly.constants', 'Blockly.registry', 'Blockly.utils.Coordinate', 'Blockly.utils.dom']);
 goog.addDependency('../../core/block_svg.js', ['Blockly.BlockSvg'], ['Blockly.ASTNode', 'Blockly.Block', 'Blockly.ContextMenu', 'Blockly.ContextMenuRegistry', 'Blockly.Events', 'Blockly.Events.BlockMove', 'Blockly.Events.Selected', 'Blockly.IASTNodeLocationSvg', 'Blockly.IBoundedElement', 'Blockly.ICopyable', 'Blockly.IDraggable', 'Blockly.Msg', 'Blockly.RenderedConnection', 'Blockly.TabNavigateCursor', 'Blockly.Tooltip', 'Blockly.Touch', 'Blockly.Xml', 'Blockly.blockAnimations', 'Blockly.blockRendering.IPathObject', 'Blockly.browserEvents', 'Blockly.connectionTypes', 'Blockly.constants', 'Blockly.utils', 'Blockly.utils.Coordinate', 'Blockly.utils.Rect', 'Blockly.utils.Svg', 'Blockly.utils.deprecation', 'Blockly.utils.dom', 'Blockly.utils.object', 'Blockly.utils.userAgent']);
 goog.addDependency('../../core/blockly.js', ['Blockly'], ['Blockly.ComponentManager', 'Blockly.DropDownDiv', 'Blockly.Events', 'Blockly.Events.BlockCreate', 'Blockly.Events.FinishedLoading', 'Blockly.Events.Ui', 'Blockly.Events.UiBase', 'Blockly.Events.VarCreate', 'Blockly.Procedures', 'Blockly.ShortcutRegistry', 'Blockly.Tooltip', 'Blockly.Touch', 'Blockly.Variables', 'Blockly.WidgetDiv', 'Blockly.WorkspaceSvg', 'Blockly.Xml', 'Blockly.browserEvents', 'Blockly.connectionTypes', 'Blockly.constants', 'Blockly.inject', 'Blockly.inputTypes', 'Blockly.utils', 'Blockly.utils.Size', 'Blockly.utils.colour', 'Blockly.utils.deprecation', 'Blockly.utils.toolbox']);
-goog.addDependency('../../core/blocks.js', ['Blockly.Blocks'], []);
+goog.addDependency('../../core/blocks.js', ['Blockly.Blocks'], [], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../core/browser_events.js', ['Blockly.browserEvents'], ['Blockly.Touch', 'Blockly.utils.global']);
 goog.addDependency('../../core/bubble.js', ['Blockly.Bubble'], ['Blockly.IBubble', 'Blockly.Scrollbar', 'Blockly.Touch', 'Blockly.Workspace', 'Blockly.browserEvents', 'Blockly.utils', 'Blockly.utils.Coordinate', 'Blockly.utils.Size', 'Blockly.utils.Svg', 'Blockly.utils.dom', 'Blockly.utils.math', 'Blockly.utils.userAgent']);
 goog.addDependency('../../core/bubble_dragger.js', ['Blockly.BubbleDragger'], ['Blockly.Bubble', 'Blockly.ComponentManager', 'Blockly.Events', 'Blockly.Events.CommentMove', 'Blockly.constants', 'Blockly.utils', 'Blockly.utils.Coordinate']);