diff --git a/libavformat/isom.c b/libavformat/isom.c
index 24e45643a5..ffe369e19d 100644
--- a/libavformat/isom.c
+++ b/libavformat/isom.c
@@ -460,11 +460,12 @@ static int mov_rewrite_dvd_sub_extradata(AVStream *st)
     char buf[256];
     int pal_s_pos = 0;
     uint8_t *src = st->codec->extradata;
+    int i;
 
     if (st->codec->extradata_size != 64)
         return 0;
 
-    for (int i = 0; i < 16; i++) {
+    for (i = 0; i < 16; i++) {
         uint32_t yuv = AV_RB32(src + i * 4);
         uint32_t rgba = yuv_to_rgba(yuv);