diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index f22c2ab70c..5950b4de44 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -2001,6 +2001,8 @@ static int mkv_write_header(AVFormatContext *s)
     }
     if ((pb->seekable & AVIO_SEEKABLE_NORMAL) && mkv->reserve_cues_space) {
         mkv->cues_pos = avio_tell(pb);
+        if (mkv->reserve_cues_space == 1)
+            mkv->reserve_cues_space++;
         put_ebml_void(pb, mkv->reserve_cues_space);
     }