diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 855d98b09ea03..2e5056ffe7fb1 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -421,7 +421,7 @@ static int mxf_read_primer_pack(void *arg, AVIOContext *pb, int tag, int size, U
         avpriv_request_sample(pb, "Primer pack item length %d", item_len);
         return AVERROR_PATCHWELCOME;
     }
-    if (item_num > 65536) {
+    if (item_num > 65536 || item_num < 0) {
         av_log(mxf->fc, AV_LOG_ERROR, "item_num %d is too large\n", item_num);
         return AVERROR_INVALIDDATA;
     }