diff --git a/packages/tswebextension/test/lib/mv2/background/mocks/mock-context.ts b/packages/tswebextension/test/lib/mv2/background/mocks/mock-context.ts
index 67922d6931..6f9aa6b90c 100644
--- a/packages/tswebextension/test/lib/mv2/background/mocks/mock-context.ts
+++ b/packages/tswebextension/test/lib/mv2/background/mocks/mock-context.ts
@@ -12,4 +12,6 @@ export class MockAppContext implements AppContext {
     configuration: ConfigurationMV2Context | undefined = undefined;
 
     startTimeMs: number | undefined = undefined;
+
+    cosmeticsInjectedOnStartup: boolean = false;
 }