diff --git a/ember-resources/src/-private/resources/ember-concurrency-task.ts b/ember-resources/src/-private/resources/ember-concurrency-task.ts
index 155f96460..d8c441e9c 100644
--- a/ember-resources/src/-private/resources/ember-concurrency-task.ts
+++ b/ember-resources/src/-private/resources/ember-concurrency-task.ts
@@ -34,7 +34,7 @@ export interface TaskInstance<Return = unknown> extends Promise<Return> {
   readonly isFinished: boolean;
   readonly isRunning: boolean;
   readonly isDropped: boolean;
-  cancel(reason?: string): Promise<void>;
+  cancel(reason?: string): void | Promise<void>;
 }
 
 // @private