diff --git a/packages/core/src/ScheduledTaskManager.ts b/packages/core/src/ScheduledTaskManager.ts
index fd2bb525a9..00396903a5 100644
--- a/packages/core/src/ScheduledTaskManager.ts
+++ b/packages/core/src/ScheduledTaskManager.ts
@@ -30,8 +30,9 @@ export class ScheduledTaskManager {
 
 	deregisterCrons(workflowId: string) {
 		const cronJobs = this.cronJobs.get(workflowId) ?? [];
-		for (const cronJob of cronJobs) {
-			cronJob.stop();
+		while (cronJobs.length) {
+			const cronJob = cronJobs.pop();
+			if (cronJob) cronJob.stop();
 		}
 	}
 
diff --git a/packages/core/test/ScheduledTaskManager.test.ts b/packages/core/test/ScheduledTaskManager.test.ts
index 3ff8837ca9..5166240856 100644
--- a/packages/core/test/ScheduledTaskManager.test.ts
+++ b/packages/core/test/ScheduledTaskManager.test.ts
@@ -56,8 +56,13 @@ describe('ScheduledTaskManager', () => {
 		scheduledTaskManager.registerCron(workflow, everyMinute, onTick);
 		scheduledTaskManager.registerCron(workflow, everyMinute, onTick);
 		scheduledTaskManager.registerCron(workflow, everyMinute, onTick);
+
+		expect(scheduledTaskManager.cronJobs.get(workflow.id)?.length).toBe(3);
+
 		scheduledTaskManager.deregisterCrons(workflow.id);
 
+		expect(scheduledTaskManager.cronJobs.get(workflow.id)?.length).toBe(0);
+
 		expect(onTick).not.toHaveBeenCalled();
 		jest.advanceTimersByTime(10 * 60 * 1000); // 10 minutes
 		expect(onTick).not.toHaveBeenCalled();