diff --git a/core/interfaces/i_procedure_block.js b/core/interfaces/i_procedure_block.js
deleted file mode 100644
index 17502c19a..000000000
--- a/core/interfaces/i_procedure_block.js
+++ /dev/null
@@ -1,43 +0,0 @@
-/**
- * @license
- * Copyright 2021 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-
-/**
- * @fileoverview The interface for a procedure block.
- */
-
-'use strict';
-
-goog.provide('Blockly.Procedures.ProcedureBlock');
-
-/**
- * A procedure block interface.
- * @interface
- */
-Blockly.Procedures.ProcedureBlock = function() {};
-
-/**
- * Returns the name of the procedure the procedure block calls.
- * @return {string}
- */
-Blockly.Procedures.ProcedureBlock.prototype.getProcedureCall;
-
-/**
- * Renames the procedure from the old name to the new name. If the procedure
- * block receives this and the old name matches the block's current name, it
- * should update itself to have the new name instead.
- * @param {string} oldName The old name of the procedure.
- * @param {string} newName The new name of hte procedure.
- */
-Blockly.Procedures.ProcedureBlock.prototype.renameProcedure;
-
-/**
- * Returns the signature of the procedure block's procedure definition.
- * @return {!Array} Tuple containing three elements:
- *     - {string} the name of the defined procedure
- *     - {!Array<string>} a list of all its arguments
- *     - {boolean} whether it has a return value or not
- */
-Blockly.Procedures.ProcedureBlock.prototype.getProcedureDef;
diff --git a/core/procedures.js b/core/procedures.js
index 03b0210b3..59c364719 100644
--- a/core/procedures.js
+++ b/core/procedures.js
@@ -25,7 +25,6 @@ goog.require('Blockly.Events.BlockChange');
 goog.require('Blockly.Field');
 goog.require('Blockly.Msg');
 goog.require('Blockly.Names');
-goog.require('Blockly.Procedures.ProcedureBlock');
 goog.require('Blockly.utils.xml');
 goog.require('Blockly.Workspace');
 goog.require('Blockly.Xml');
@@ -48,6 +47,16 @@ Blockly.Procedures.NAME_TYPE = Blockly.PROCEDURE_CATEGORY_NAME;
  */
 Blockly.Procedures.DEFAULT_ARG = 'x';
 
+/**
+ * Procedure block type.
+ * @typedef {{
+ *    getProcedureCall: function():string,
+ *    renameProcedure: function(string,string),
+ *    getProcedureDef: function():!Array
+ * }}
+ */
+Blockly.Procedures.ProcedureBlock;
+
 /**
  * Find all user-created procedure definitions in a workspace.
  * @param {!Blockly.Workspace} root Root workspace.