diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 4d4d0cd024..d0bd1824e1 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -4475,7 +4475,8 @@ static int mov_write_sidx_tag(AVIOContext *pb,
 {
     int64_t pos = avio_tell(pb), offset_pos, end_pos;
     int64_t presentation_time, duration, offset;
-    int starts_with_SAP, i, entries;
+    unsigned starts_with_SAP;
+    int i, entries;
 
     if (track->entry) {
         entries = 1;