diff --git a/sys/kern/subr_gtaskqueue.c b/sys/kern/subr_gtaskqueue.c
index b80c13d8948ada..d5d16327fae42e 100644
--- a/sys/kern/subr_gtaskqueue.c
+++ b/sys/kern/subr_gtaskqueue.c
@@ -672,6 +672,7 @@ taskqgroup_attach_deferred(struct taskqgroup *qgroup, struct grouptask *gtask)
 
 	LIST_INSERT_HEAD(&qgroup->tqg_queue[qid].tgc_tasks, gtask,
 			 gt_list);
+	MPASS(qgroup->tqg_queue[qid].tgc_taskq != NULL);
 	gtask->gt_taskqueue = qgroup->tqg_queue[qid].tgc_taskq;
 	mtx_unlock(&qgroup->tqg_lock);
 }
@@ -736,6 +737,7 @@ taskqgroup_attach_cpu_deferred(struct taskqgroup *qgroup, struct grouptask *gtas
 	}
 	qgroup->tqg_queue[qid].tgc_cnt++;
 	LIST_INSERT_HEAD(&qgroup->tqg_queue[qid].tgc_tasks, gtask, gt_list);
+	MPASS(qgroup->tqg_queue[qid].tgc_taskq != NULL);
 	gtask->gt_taskqueue = qgroup->tqg_queue[qid].tgc_taskq;
 	mtx_unlock(&qgroup->tqg_lock);