diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index c18a25951c..0a6d937a0a 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -600,7 +600,7 @@ static int mxf_decrypt_triplet(AVFormatContext *s, AVPacket *pkt, KLVPacket *klv
         return AVERROR_INVALIDDATA;
     // enc. code
     size = klv_decode_ber_length(pb);
-    if (size < 32 || size - 32 < orig_size)
+    if (size < 32 || size - 32 < orig_size || (int)orig_size != orig_size)
         return AVERROR_INVALIDDATA;
     avio_read(pb, ivec, 16);
     avio_read(pb, tmpbuf, 16);