diff --git a/ChangeLog b/ChangeLog
index fc8a4018fe..b4d45b873c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2004-12-18  Ronald S. Bultje  <rbultje@ronald.bitfreak.net>
+
+	* gst/matroska/matroska-demux.c:
+	(gst_matroska_demux_parse_blockgroup):
+	  Fix possible crasher.
+
 2004-12-18  Ronald S. Bultje  <rbultje@ronald.bitfreak.net>
 
 	* gst/matroska/matroska-demux.c: (gst_matroska_ebmlnum_uint),
diff --git a/gst/matroska/matroska-demux.c b/gst/matroska/matroska-demux.c
index 03ba7ce110..e4353c4aeb 100644
--- a/gst/matroska/matroska-demux.c
+++ b/gst/matroska/matroska-demux.c
@@ -1884,7 +1884,8 @@ gst_matroska_demux_parse_blockgroup (GstMatroskaDemux * demux,
                   lace_size[n] = lace_size[n - 1] + snum;
                   total += lace_size[n];
                 }
-                lace_size[n] = size - total;
+                if (n < laces)
+                  lace_size[n] = size - total;
                 break;
               }
             }