diff --git a/packages/frontend-test-utils/src/app/createExtensionTester.tsx b/packages/frontend-test-utils/src/app/createExtensionTester.tsx
index f9c1b3cb89..b520ee35bb 100644
--- a/packages/frontend-test-utils/src/app/createExtensionTester.tsx
+++ b/packages/frontend-test-utils/src/app/createExtensionTester.tsx
@@ -110,6 +110,8 @@ export class ExtensionTester<UOutput extends AnyExtensionDataRef> {
 
     const definition = {
       ...extension,
+      // If no namespace is set, we default to "test"
+      namespace: namespace ?? 'test',
       // setting name "test" as fallback
       name: !namespace && !name ? 'test' : name,
     };