diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index aff2fa2bec..e4db145d94 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -3331,7 +3331,8 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, AVBufferRef *buf
     st = track->stream;
     if (st->discard >= AVDISCARD_ALL)
         return res;
-    av_assert1(block_duration != AV_NOPTS_VALUE);
+    if (block_duration > INT64_MAX)
+        block_duration = INT64_MAX;
 
     block_time = sign_extend(AV_RB16(data), 16);
     data      += 2;