diff --git a/libavcodec/h264_refs.c b/libavcodec/h264_refs.c
index 444849ae11..7fafb826d7 100644
--- a/libavcodec/h264_refs.c
+++ b/libavcodec/h264_refs.c
@@ -368,6 +368,8 @@ int ff_h264_build_ref_list(H264Context *h, H264SliceContext *sl)
                 }
                 break;
             }
+            default:
+                av_assert1(0);
             }
 
             if (i < 0) {