diff --git a/libavformat/mlvdec.c b/libavformat/mlvdec.c
index db7576bfdf..6550e866a3 100644
--- a/libavformat/mlvdec.c
+++ b/libavformat/mlvdec.c
@@ -239,7 +239,7 @@ static int scan_file(AVFormatContext *avctx, AVStream *vst, AVStream *ast, int f
         } else if (type == MKTAG('N','U','L','L')) {
         } else if (type == MKTAG('M','L','V','I')) { /* occurs when MLV and Mnn files are concatenated */
         } else {
-            av_log(avctx, AV_LOG_INFO, "unsupported tag %c%c%c%c, size %d\n", type&0xFF, (type>>8)&0xFF, (type>>16)&0xFF, (type>>24)&0xFF, size);
+            av_log(avctx, AV_LOG_INFO, "unsupported tag %c%c%c%c, size %u\n", type&0xFF, (type>>8)&0xFF, (type>>16)&0xFF, (type>>24)&0xFF, size);
         }
         avio_skip(pb, size);
     }