diff --git a/sys/xvimage/xvimagesink.c b/sys/xvimage/xvimagesink.c
index 4b50d1ebe1..e5e0345c3e 100644
--- a/sys/xvimage/xvimagesink.c
+++ b/sys/xvimage/xvimagesink.c
@@ -1087,6 +1087,7 @@ gst_xvimagesink_get_xv_support (GstXvImageSink * xvimagesink,
         break;
       }
       default:
+        vformat = GST_VIDEO_FORMAT_UNKNOWN;
         g_assert_not_reached ();
         break;
     }