diff --git a/test-packages/v2-ts-ember-addon/src/co-located-declarations/foo.gjs b/test-packages/v2-ts-ember-addon/src/co-located-declarations/foo.gjs
new file mode 100644
index 00000000..b45145f9
--- /dev/null
+++ b/test-packages/v2-ts-ember-addon/src/co-located-declarations/foo.gjs
@@ -0,0 +1 @@
+export const CLDFoo = <template>{{yield 2}}</template>;
diff --git a/test-packages/v2-ts-ember-addon/src/co-located-declarations/foo.gjs.d.ts b/test-packages/v2-ts-ember-addon/src/co-located-declarations/foo.gjs.d.ts
new file mode 100644
index 00000000..a6b5c19f
--- /dev/null
+++ b/test-packages/v2-ts-ember-addon/src/co-located-declarations/foo.gjs.d.ts
@@ -0,0 +1,7 @@
+import type { ComponentLike } from '@glint/template';
+
+export declare const CLDFoo: ComponentLike<{
+  Blocks: {
+    default: [two: number];
+  };
+}>;
diff --git a/test-packages/v2-ts-ember-addon/src/co-located-declarations/usage.gts b/test-packages/v2-ts-ember-addon/src/co-located-declarations/usage.gts
new file mode 100644
index 00000000..d0064a47
--- /dev/null
+++ b/test-packages/v2-ts-ember-addon/src/co-located-declarations/usage.gts
@@ -0,0 +1,7 @@
+import { CLDFoo } from './foo.gjs';
+
+export const Usage = <template>
+  <CLDFoo as |two|>
+    {{two}}
+  </CLDFoo>
+</template>;
diff --git a/test-packages/v2-ts-ember-addon/src/index.ts b/test-packages/v2-ts-ember-addon/src/index.ts
index f5783415..a91c6800 100644
--- a/test-packages/v2-ts-ember-addon/src/index.ts
+++ b/test-packages/v2-ts-ember-addon/src/index.ts
@@ -1 +1,3 @@
 export { Foo } from './foo.gts';
+export { Usage } from './co-located-declarations/usage.gts';
+export { CLDFoo } from './co-located-declarations/foo.gjs';
diff --git a/test-packages/v2-ts-ember-addon/test-build.mjs b/test-packages/v2-ts-ember-addon/test-build.mjs
index 55412d6e..906e8411 100644
--- a/test-packages/v2-ts-ember-addon/test-build.mjs
+++ b/test-packages/v2-ts-ember-addon/test-build.mjs
@@ -19,15 +19,20 @@ assertReady();
 
 for await (const entry of glob('{dist,declarations}/**/*.{js,d.ts}')) {
   console.log(`Checking ${entry}`);
-  let buffer = readFile(entry);
+  let buffer = await readFile(entry);
   let content = buffer.toString();
 
-  let hasForbiddenExtensions = content.match(/\.gts/);
+  let hasGts = content.match(/\.gts/g);
+  let hasGjs = content.match(/\.gjs/g);
 
   check(
-    !hasForbiddenExtensions,
+    !hasGts,
     `Expected ${entry} to not have the .gts extension anywhere in the file`,
   );
+  check(
+    !hasGjs,
+    `Expected ${entry} to not have the .gjs extension anywhere in the file`,
+  );
 }
 
 assertDone();
@@ -59,6 +64,8 @@ function assertReady() {
 }
 
 function assertDone() {
+  console.log('\n\n');
+
   assertReady();
 
   console.info(`No issues were found.`);
diff --git a/test-packages/v2-ts-ember-addon/tsconfig.json b/test-packages/v2-ts-ember-addon/tsconfig.json
index ef0c5abe..40f8a34f 100644
--- a/test-packages/v2-ts-ember-addon/tsconfig.json
+++ b/test-packages/v2-ts-ember-addon/tsconfig.json
@@ -7,6 +7,7 @@
   "extends": "@ember/app-tsconfig",
   "include": ["src/**/*", "tests/**/*", "unpublished-development-types/**/*"],
   "compilerOptions": {
+    "allowArbitraryExtensions": true,
     "rootDir": ".",
     "types": [
       "ember-source/types",