diff --git a/sys/dev/drm/include/drm/ttm/ttm_bo_driver.h b/sys/dev/drm/include/drm/ttm/ttm_bo_driver.h
index ca05c2a..596cef6 100644
--- a/sys/dev/drm/include/drm/ttm/ttm_bo_driver.h
+++ b/sys/dev/drm/include/drm/ttm/ttm_bo_driver.h
@@ -37,6 +37,7 @@
 #include <drm/drm_mm.h>
 #include <drm/drm_global.h>
 #include <sys/tree.h>
+#include <sys/mutex2.h>
 
 struct ttm_backend_func {
 	/**
@@ -561,6 +562,7 @@ struct ttm_bo_device {
 	 * Internal protection.
 	 */
 
+	struct mtx wq_mtx;
 	struct timeout_task wq;
 
 	bool need_dma32;
diff --git a/sys/dev/drm/ttm/ttm_bo.c b/sys/dev/drm/ttm/ttm_bo.c
index c743361..2c4939b 100644
--- a/sys/dev/drm/ttm/ttm_bo.c
+++ b/sys/dev/drm/ttm/ttm_bo.c
@@ -592,8 +592,10 @@ static void ttm_bo_cleanup_refs_or_queue(struct ttm_buffer_object *bo)
 		driver->sync_obj_flush(sync_obj);
 		driver->sync_obj_unref(&sync_obj);
 	}
+	mtx_lock(&bdev->wq_mtx);
 	taskqueue_enqueue_timeout(taskqueue_thread[0], &bdev->wq,
 	    ((hz / 100) < 1) ? 1 : hz / 100);
+	mtx_unlock(&bdev->wq_mtx);
 }
 
 /**
@@ -753,8 +755,10 @@ static void ttm_bo_delayed_workqueue(void *arg, int pending __unused)
 	struct ttm_bo_device *bdev = arg;
 
 	if (ttm_bo_delayed_delete(bdev, false)) {
+		mtx_lock(&bdev->wq_mtx);
 		taskqueue_enqueue_timeout(taskqueue_thread[0], &bdev->wq,
 		    ((hz / 100) < 1) ? 1 : hz / 100);
+		mtx_unlock(&bdev->wq_mtx);
 	}
 }
 
@@ -819,8 +823,9 @@ int ttm_bo_lock_delayed_workqueue(struct ttm_bo_device *bdev)
 	int pending;
 
 	taskqueue_cancel_timeout(taskqueue_thread[0], &bdev->wq, &pending);
-	if (pending)
+	if (pending) {
 		taskqueue_drain_timeout(taskqueue_thread[0], &bdev->wq);
+	}
 	return (pending);
 }
 EXPORT_SYMBOL(ttm_bo_lock_delayed_workqueue);
@@ -828,8 +833,10 @@ EXPORT_SYMBOL(ttm_bo_lock_delayed_workqueue);
 void ttm_bo_unlock_delayed_workqueue(struct ttm_bo_device *bdev, int resched)
 {
 	if (resched) {
+		mtx_lock(&bdev->wq_mtx);
 		taskqueue_enqueue_timeout(taskqueue_thread[0], &bdev->wq,
 		    ((hz / 100) < 1) ? 1 : hz / 100);
+		mtx_unlock(&bdev->wq_mtx);
 	}
 }
 EXPORT_SYMBOL(ttm_bo_unlock_delayed_workqueue);
@@ -1608,8 +1615,9 @@ int ttm_bo_device_release(struct ttm_bo_device *bdev)
 	list_del(&bdev->device_list);
 	lockmgr(&glob->device_list_mutex, LK_RELEASE);
 
-	if (taskqueue_cancel_timeout(taskqueue_thread[0], &bdev->wq, NULL))
+	if (taskqueue_cancel_timeout(taskqueue_thread[0], &bdev->wq, NULL)) {
 		taskqueue_drain_timeout(taskqueue_thread[0], &bdev->wq);
+	}
 
 	while (ttm_bo_delayed_delete(bdev, true))
 		;
@@ -1657,6 +1665,7 @@ int ttm_bo_device_init(struct ttm_bo_device *bdev,
 	if (unlikely(ret != 0))
 		goto out_no_addr_mm;
 
+	mtx_init(&bdev->wq_mtx);
 	TIMEOUT_TASK_INIT(taskqueue_thread[0], &bdev->wq, 0,
 	    ttm_bo_delayed_workqueue, bdev);
 	INIT_LIST_HEAD(&bdev->ddestroy);