diff --git a/jetstream/src/types.ts b/jetstream/src/types.ts
index a65d18d5..759cc993 100644
--- a/jetstream/src/types.ts
+++ b/jetstream/src/types.ts
@@ -463,7 +463,7 @@ export type IdleHeartbeat = {
   idle_heartbeat?: number;
 };
 
-export type ConsumerCallbackFn = (r: JsMsg) => void;
+export type ConsumerCallbackFn = (r: JsMsg) => void | Promise<never>;
 export type ConsumeCallback = {
   /**
    * Process messages using a callback instead of an iterator. Note that when using callbacks,