diff --git a/libavformat/hls.c b/libavformat/hls.c
index 44afdaab42..06bc46c23f 100644
--- a/libavformat/hls.c
+++ b/libavformat/hls.c
@@ -914,7 +914,7 @@ static int parse_playlist(HLSContext *c, const char *url,
                 if (has_iv) {
                     memcpy(seg->iv, iv, sizeof(iv));
                 } else {
-                    int64_t seq = pls->start_seq_no + pls->n_segments;
+                    uint64_t seq = pls->start_seq_no + (uint64_t)pls->n_segments;
                     memset(seg->iv, 0, sizeof(seg->iv));
                     AV_WB64(seg->iv + 8, seq);
                 }