diff --git a/packages/backend-core/src/queue/inMemoryQueue.ts b/packages/backend-core/src/queue/inMemoryQueue.ts
index b80aece418..ec1d9d4a90 100644
--- a/packages/backend-core/src/queue/inMemoryQueue.ts
+++ b/packages/backend-core/src/queue/inMemoryQueue.ts
@@ -128,6 +128,7 @@ class InMemoryQueue {
 
   on() {
     // do nothing
+    return this
   }
 
   async waitForCompletion() {