diff --git a/libavformat/mov.c b/libavformat/mov.c
index 0e37b99c86..b62eecdd80 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -4353,12 +4353,13 @@ static int mov_read_keys(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     for (i = 1; i <= count; ++i) {
         uint32_t key_size = avio_rb32(pb);
         uint32_t type = avio_rl32(pb);
-        if (key_size < 8) {
+        if (key_size < 8 || key_size > atom.size) {
             av_log(c->fc, AV_LOG_ERROR,
                    "The key# %"PRIu32" in meta has invalid size:"
                    "%"PRIu32"\n", i, key_size);
             return AVERROR_INVALIDDATA;
         }
+        atom.size -= key_size;
         key_size -= 8;
         if (type != MKTAG('m','d','t','a')) {
             avio_skip(pb, key_size);