diff --git a/libavcodec/vorbis.c b/libavcodec/vorbis.c
index 61c395e71e..80d5198c62 100644
--- a/libavcodec/vorbis.c
+++ b/libavcodec/vorbis.c
@@ -73,7 +73,7 @@ int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes, unsigned num)
     if (bits[p] > 32)
         return AVERROR_INVALIDDATA;
     for (i = 0; i < bits[p]; ++i)
-        exit_at_level[i+1] = 1 << i;
+        exit_at_level[i+1] = 1u << i;
 
 #ifdef DEBUG
     av_log(NULL, AV_LOG_INFO, " %u. of %u code len %d code %d - ", p, num, bits[p], codes[p]);