diff --git a/plugins/dev-tools/package.json b/plugins/dev-tools/package.json
index cbcd3746c0..ac9ee350bc 100644
--- a/plugins/dev-tools/package.json
+++ b/plugins/dev-tools/package.json
@@ -57,7 +57,7 @@
     "blockly": "^8.0.0"
   },
   "peerDependencies": {
-    "blockly": ">=8 <9"
+    "blockly": ">=7 <9"
   },
   "publishConfig": {
     "access": "public",
diff --git a/plugins/dev-tools/src/block_test_helpers.mocha.js b/plugins/dev-tools/src/block_test_helpers.mocha.js
index 95880fda05..ae74428357 100644
--- a/plugins/dev-tools/src/block_test_helpers.mocha.js
+++ b/plugins/dev-tools/src/block_test_helpers.mocha.js
@@ -211,8 +211,25 @@ export const runSerializationTestSuite = (testCases) => {
     });
     suite('xml round-trip', function() {
       setup(function() {
-        sinon.stub(Blockly.utils.idGenerator.TEST_ONLY, 'genUid')
-            .returns('1');
+        // The genUid is undergoing change as part of the 2021Q3
+        // goog.module migration:
+        //
+        // - It is being moved from Blockly.utils to
+        //   Blockly.utils.idGenerator (which itself is being renamed
+        //   from IdGenerator).
+        // - For compatibility with changes to the module system (from
+        //   goog.provide to goog.module and in future to ES modules),
+        //   .genUid is now a wrapper around .TEST_ONLY.genUid, which
+        //   can be safely stubbed by sinon or other similar
+        //   frameworks in a way that will continue to work.
+        if (Blockly.utils.idGenerator &&
+            Blockly.utils.idGenerator.TEST_ONLY) {
+          sinon.stub(Blockly.utils.idGenerator.TEST_ONLY, 'genUid')
+              .returns('1');
+        } else {
+          // Fall back to stubbing original version on Blockly.utils.
+          sinon.stub(Blockly.utils, 'genUid').returns('1');
+        }
       });
 
       teardown(function() {
diff --git a/plugins/dev-tools/src/index.js b/plugins/dev-tools/src/index.js
index 6cd083b8f9..3c1cfdb2fe 100644
--- a/plugins/dev-tools/src/index.js
+++ b/plugins/dev-tools/src/index.js
@@ -29,7 +29,13 @@ if (typeof window !== 'undefined') {
 
 // Export Blockly into the global namespace to make it easier to debug from the
 // console.
-globalThis.Blockly = Blockly;
+if (Blockly.utils.global) {
+  if (Blockly.utils.global.globalThis) {
+    Blockly.utils.global.globalThis.Blockly = Blockly;
+  } else {
+    Blockly.utils.global.Blockly = Blockly;
+  }
+}
 
 export {
   addCodeEditor,
diff --git a/plugins/eslint-config/index.js b/plugins/eslint-config/index.js
index 7532393790..1b2aa6303a 100644
--- a/plugins/eslint-config/index.js
+++ b/plugins/eslint-config/index.js
@@ -18,7 +18,7 @@ module.exports = {
   env: {
     browser: true,
     commonjs: true,
-    es2020: true,
+    es6: true,
     node: true,
   },