diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index e8f70f96c1..4690e01d3c 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -2040,7 +2040,8 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
                 }
             } else {
                 MatroskaTrackEncoding *encodings = track->encodings.elem;
-                int offset = 0, pkt_size = lace_size[n];
+                int offset = 0;
+                uint32_t pkt_size = lace_size[n];
                 uint8_t *pkt_data = data;
 
                 if (pkt_size > size) {