diff --git a/demux/demux_mkv.c b/demux/demux_mkv.c
index 004efebfc0..443cec03a5 100644
--- a/demux/demux_mkv.c
+++ b/demux/demux_mkv.c
@@ -1110,8 +1110,8 @@ static int demux_mkv_read_chapters(struct demuxer *demuxer)
                 }
             }
 
-            MP_DBG(demuxer, "Chapter %u from %02d:%02d:%02d.%03d "
-                   "to %02d:%02d:%02d.%03d, %s\n", i,
+            MP_DBG(demuxer, "Chapter %u from %02d:%02d:%02d.%09d "
+                   "to %02d:%02d:%02d.%09d, %s\n", i,
                    (int) (chapter.start / 60 / 60 / 1000000000),
                    (int) ((chapter.start / 60 / 1000000000) % 60),
                    (int) ((chapter.start / 1000000000) % 60),