diff --git a/libavformat/mov.c b/libavformat/mov.c
index 9291195a8f..d551a0f8e0 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -5023,6 +5023,7 @@ static int mov_read_keys(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 
     avio_skip(pb, 4);
     count = avio_rb32(pb);
+    atom.size -= 8;
     if (count > UINT_MAX / sizeof(*c->meta_keys) - 1) {
         av_log(c->fc, AV_LOG_ERROR,
                "The 'keys' atom with the invalid key count: %"PRIu32"\n", count);