diff --git a/ffmpeg_opt.c b/ffmpeg_opt.c
index 7505ba9a5d..41db1b2456 100644
--- a/ffmpeg_opt.c
+++ b/ffmpeg_opt.c
@@ -443,6 +443,8 @@ static int copy_metadata(char *outspec, char *inspec, AVFormatContext *oc, AVFor
             meta = &context->programs[index]->metadata;\
             break;\
         default: av_assert0(0);\
+        case 's':\
+            break;\
         }\
 
     SET_DICT(type_in, meta_in, ic, idx_in);