diff --git a/libavformat/asfdec_o.c b/libavformat/asfdec_o.c
index b4b2698368..6174cfae2c 100644
--- a/libavformat/asfdec_o.c
+++ b/libavformat/asfdec_o.c
@@ -1679,6 +1679,9 @@ static int detect_unknown_subobject(AVFormatContext *s, int64_t offset, int64_t
     ff_asf_guid guid;
     int ret;
 
+    if (offset > INT64_MAX - size)
+        return AVERROR_INVALIDDATA;
+
     while (avio_tell(pb) <= offset + size) {
         if (avio_tell(pb) == asf->offset)
             break;