diff --git a/core/interfaces/i_connection_checker.js b/core/interfaces/i_connection_checker.js
index 4b6120da1..527dec4c5 100644
--- a/core/interfaces/i_connection_checker.js
+++ b/core/interfaces/i_connection_checker.js
@@ -11,7 +11,8 @@
  */
 'use strict';
 
-goog.provide('Blockly.IConnectionChecker');
+goog.module('Blockly.IConnectionChecker');
+goog.module.declareLegacyNamespace();
 
 goog.requireType('Blockly.Connection');
 goog.requireType('Blockly.RenderedConnection');
@@ -21,7 +22,7 @@ goog.requireType('Blockly.RenderedConnection');
  * Class for connection type checking logic.
  * @interface
  */
-Blockly.IConnectionChecker = function() {};
+const IConnectionChecker = function() {};
 
 /**
  * Check whether the current connection can connect with the target
@@ -35,7 +36,7 @@ Blockly.IConnectionChecker = function() {};
  * @return {boolean} Whether the connection is legal.
  * @public
  */
-Blockly.IConnectionChecker.prototype.canConnect;
+IConnectionChecker.prototype.canConnect;
 
 /**
  * Checks whether the current connection can connect with the target
@@ -50,7 +51,7 @@ Blockly.IConnectionChecker.prototype.canConnect;
  *    an error code otherwise.
  * @public
  */
-Blockly.IConnectionChecker.prototype.canConnectWithReason;
+IConnectionChecker.prototype.canConnectWithReason;
 
 /**
  * Helper method that translates a connection error code into a string.
@@ -61,7 +62,7 @@ Blockly.IConnectionChecker.prototype.canConnectWithReason;
  * @return {string} A developer-readable error string.
  * @public
  */
-Blockly.IConnectionChecker.prototype.getErrorMessage;
+IConnectionChecker.prototype.getErrorMessage;
 
 /**
  * Check that connecting the given connections is safe, meaning that it would
@@ -71,7 +72,7 @@ Blockly.IConnectionChecker.prototype.getErrorMessage;
  * @return {number} An enum with the reason this connection is safe or unsafe.
  * @public
  */
-Blockly.IConnectionChecker.prototype.doSafetyChecks;
+IConnectionChecker.prototype.doSafetyChecks;
 
 /**
  * Check whether this connection is compatible with another connection with
@@ -82,7 +83,7 @@ Blockly.IConnectionChecker.prototype.doSafetyChecks;
  * @return {boolean} True if the connections share a type.
  * @public
  */
-Blockly.IConnectionChecker.prototype.doTypeChecks;
+IConnectionChecker.prototype.doTypeChecks;
 
 /**
  * Check whether this connection can be made by dragging.
@@ -92,4 +93,6 @@ Blockly.IConnectionChecker.prototype.doTypeChecks;
  * @return {boolean} True if the connection is allowed during a drag.
  * @public
  */
-Blockly.IConnectionChecker.prototype.doDragChecks;
+IConnectionChecker.prototype.doDragChecks;
+
+exports = IConnectionChecker;
diff --git a/tests/deps.js b/tests/deps.js
index 0b641086e..aa3fc9275 100644
--- a/tests/deps.js
+++ b/tests/deps.js
@@ -81,7 +81,7 @@ goog.addDependency('../../core/interfaces/i_block_dragger.js', ['Blockly.IBlockD
 goog.addDependency('../../core/interfaces/i_bounded_element.js', ['Blockly.IBoundedElement'], [], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../core/interfaces/i_bubble.js', ['Blockly.IBubble'], ['Blockly.IContextMenu', 'Blockly.IDraggable'], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../core/interfaces/i_component.js', ['Blockly.IComponent'], [], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../core/interfaces/i_connection_checker.js', ['Blockly.IConnectionChecker'], []);
+goog.addDependency('../../core/interfaces/i_connection_checker.js', ['Blockly.IConnectionChecker'], [], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../core/interfaces/i_contextmenu.js', ['Blockly.IContextMenu'], [], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../core/interfaces/i_copyable.js', ['Blockly.ICopyable'], [], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../core/interfaces/i_deletable.js', ['Blockly.IDeletable'], [], {'lang': 'es6', 'module': 'goog'});