diff --git a/packages/shared-internals/src/colocation.ts b/packages/shared-internals/src/colocation.ts
index b83f11a9a..3c635a7df 100644
--- a/packages/shared-internals/src/colocation.ts
+++ b/packages/shared-internals/src/colocation.ts
@@ -7,7 +7,7 @@ export function syntheticJStoHBS(source: string): string | null {
   // only ever JS (never TS or anything else). And extensionless imports are
   // handled by the default resolving system doing extension search.
   if (cleanUrl(source).endsWith('.js')) {
-    return source.replace(/.js(\?.*)?/, '.hbs$1');
+    return source.replace(/\.js(\?.*)?$/, '.hbs$1');
   }
 
   return null;
diff --git a/packages/shared-internals/tests/colocation.test.ts b/packages/shared-internals/tests/colocation.test.ts
new file mode 100644
index 000000000..9bdd22bb2
--- /dev/null
+++ b/packages/shared-internals/tests/colocation.test.ts
@@ -0,0 +1,25 @@
+import { syntheticJStoHBS } from '../src';
+
+describe('colocation utils', function () {
+  describe('syntheticJStoHBS', function () {
+    test('it returns .hbs files for .js', function () {
+      const testCases = [
+        ['foo.js', 'foo.hbs'],
+        ['foo.js?qp', 'foo.hbs?qp'],
+        ['foo/json.js', 'foo/json.hbs'],
+      ];
+
+      for (const [from, to] of testCases) {
+        expect(syntheticJStoHBS(from)).toEqual(to);
+      }
+    });
+
+    test('it ignores non .js files', function () {
+      const testCases = ['foo.ts', 'foo.hbs', 'foo.js.xxx'];
+
+      for (const from of testCases) {
+        expect(syntheticJStoHBS(from)).toEqual(null);
+      }
+    });
+  });
+});