diff --git a/types/observer-mixin.d.ts b/types/observer-mixin.d.ts
index 81eb768b8..b39c61605 100644
--- a/types/observer-mixin.d.ts
+++ b/types/observer-mixin.d.ts
@@ -21,7 +21,7 @@ export interface OperationHookContext<T extends typeof ModelBase> {
 
 export type Listener<Ctx = OperationHookContext<typeof ModelBase>> = (
   ctx: Ctx, next: (err?: any) => void
-) => void;
+) => PromiseOrVoid<void>;
 
 export interface ObserverMixin {
   /**