diff --git a/test/source/test.ts b/test/source/test.ts
index 7a7157498c2..7554f3000ba 100644
--- a/test/source/test.ts
+++ b/test/source/test.ts
@@ -63,9 +63,10 @@ const testWithBrowser = (
   flag?: 'FAILING'
 ): Implementation<unknown[]> => {
   return async (t: AvaContext) => {
+    let closeMockApi: (() => Promise<void>) | undefined;
     if (isMock) {
       const mockApi = await startMockApiAndCopyBuild(t);
-      t.closeMockApi = mockApi.close;
+      closeMockApi = mockApi.close;
     }
     await browserPool.withNewBrowserTimeoutAndRetry(
       async (t, browser) => {
@@ -83,8 +84,8 @@ const testWithBrowser = (
       consts,
       flag
     );
-    if (t.closeMockApi) {
-      await t.closeMockApi();
+    if (closeMockApi) {
+      await closeMockApi();
     }
     t.pass();
   };
diff --git a/test/source/tests/tooling/index.ts b/test/source/tests/tooling/index.ts
index 0951e06e4f0..dae9c25a0b6 100644
--- a/test/source/tests/tooling/index.ts
+++ b/test/source/tests/tooling/index.ts
@@ -12,7 +12,6 @@ export type AvaContext = ExecutionContext<unknown> & {
   attemptText?: string;
   extensionDir?: string;
   urls?: TestUrls;
-  closeMockApi?: () => Promise<void>;
 };
 
 const MAX_ATT_SIZE = 5 * 1024 * 1024;