diff --git a/libavfilter/vf_uspp.c b/libavfilter/vf_uspp.c
index d0ce63e02f..7526fde806 100644
--- a/libavfilter/vf_uspp.c
+++ b/libavfilter/vf_uspp.c
@@ -187,6 +187,7 @@ static inline int norm_qscale(int qscale, int type)
     case FF_QSCALE_TYPE_MPEG2: return qscale >> 1;
     case FF_QSCALE_TYPE_H264:  return qscale >> 2;
     case FF_QSCALE_TYPE_VP56:  return (63 - qscale + 2) >> 2;
+    default: av_assert0(0);
     }
     return qscale;
 }