diff --git a/libavformat/flvdec.c b/libavformat/flvdec.c
index 8465eb57d5..d9bea917d7 100644
--- a/libavformat/flvdec.c
+++ b/libavformat/flvdec.c
@@ -858,7 +858,7 @@ retry:
         orig_size =
         size = avio_rb24(s->pb);
         dts  = avio_rb24(s->pb);
-        dts |= avio_r8(s->pb) << 24;
+        dts |= (unsigned)avio_r8(s->pb) << 24;
         av_log(s, AV_LOG_TRACE, "type:%d, size:%d, last:%d, dts:%"PRId64" pos:%"PRId64"\n", type, size, last, dts, avio_tell(s->pb));
         if (avio_feof(s->pb))
             return AVERROR_EOF;