diff --git a/sys/dev/drm/drm_fb_helper.c b/sys/dev/drm/drm_fb_helper.c
--- a/sys/dev/drm/drm_fb_helper.c
+++ b/sys/dev/drm/drm_fb_helper.c
@@ -2175,6 +2175,8 @@
 create_mode:
 	mode = drm_mode_create_from_cmdline_mode(fb_helper_conn->connector->dev,
 						 cmdline_mode);
+	if (!mode)
+		return NULL;
 	list_add(&mode->head, &fb_helper_conn->connector->modes);
 	return mode;
 }