diff --git a/sys/dev/pci/drm/ttm/tests/ttm_bo_test.c b/sys/dev/pci/drm/ttm/tests/ttm_bo_test.c
index 6c77550c51a..40a55f81bf4 100644
--- a/sys/dev/pci/drm/ttm/tests/ttm_bo_test.c
+++ b/sys/dev/pci/drm/ttm/tests/ttm_bo_test.c
@@ -222,13 +222,13 @@ static void ttm_bo_reserve_interrupted(struct kunit *test)
 		KUNIT_FAIL(test, "Couldn't create ttm bo reserve task\n");
 
 	/* Take a lock so the threaded reserve has to wait */
-	mutex_lock(&bo->base.resv->lock.base);
+	dma_resv_lock(bo->base.resv, NULL);
 
 	wake_up_process(task);
 	msleep(20);
 	err = kthread_stop(task);
 
-	mutex_unlock(&bo->base.resv->lock.base);
+	dma_resv_unlock(bo->base.resv);
 
 	KUNIT_ASSERT_EQ(test, err, -ERESTARTSYS);
 }