diff --git a/sys/dev/drm2/drm_fops.c b/sys/dev/drm2/drm_fops.c
index 5d040e92ed1..316d21a8e73 100644
--- a/sys/dev/drm2/drm_fops.c
+++ b/sys/dev/drm2/drm_fops.c
@@ -536,7 +536,7 @@ void
 drm_event_wakeup(struct drm_pending_event *e)
 {
 	struct drm_file *file_priv;
-	struct drm_device *dev;
+	struct drm_device *dev __diagused;
 
 	file_priv = e->file_priv;
 	dev = file_priv->minor->dev;
diff --git a/sys/dev/drm2/ttm/ttm_lock.c b/sys/dev/drm2/ttm/ttm_lock.c
index 9a8cafbf2ab..1884acb1211 100644
--- a/sys/dev/drm2/ttm/ttm_lock.c
+++ b/sys/dev/drm2/ttm/ttm_lock.c
@@ -245,7 +245,7 @@ static void ttm_vt_lock_remove(struct ttm_base_object **p_base)
 {
 	struct ttm_base_object *base = *p_base;
 	struct ttm_lock *lock = container_of(base, struct ttm_lock, base);
-	int ret;
+	int ret __diagused;
 
 	*p_base = NULL;
 	ret = __ttm_vt_unlock(lock);
diff --git a/sys/dev/drm2/ttm/ttm_tt.c b/sys/dev/drm2/ttm/ttm_tt.c
index 55131c73bdc..d52df50adeb 100644
--- a/sys/dev/drm2/ttm/ttm_tt.c
+++ b/sys/dev/drm2/ttm/ttm_tt.c
@@ -243,7 +243,7 @@ void ttm_dma_tt_fini(struct ttm_dma_tt *ttm_dma)
 
 void ttm_tt_unbind(struct ttm_tt *ttm)
 {
-	int ret;
+	int ret __diagused;
 
 	if (ttm->state == tt_bound) {
 		ret = ttm->func->unbind(ttm);