diff --git a/libavformat/mov.c b/libavformat/mov.c
index 02b8aeb856..bfc5c44d87 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -385,7 +385,7 @@ static int mov_read_udta_string(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 
     if (!key)
         return 0;
-    if (atom.size < 0)
+    if (atom.size < 0 || str_size >= INT_MAX/2)
         return AVERROR_INVALIDDATA;
 
     str_size = FFMIN3(sizeof(str)-1, str_size, atom.size);