diff --git a/ChangeLog b/ChangeLog
index b717517041..1ff78f16eb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2005-11-10  Josef Zlomek  <josef dot zlomek at xeris dot cz>
+
+	Reviewed by: Tim-Philipp Müller  <tim at centricular dot net>
+
+	* gst/matroska/matroska-mux.c: (gst_matroska_mux_write_data):
+	  Don't try to ready buffer duration from buffer that we don't
+	  own any  longer and that might already have been unreffed.
+	  (#321136)
+
 2005-11-09  Zeeshan Ali  <zeenix@gmail.com>
 
 	* gst/flx/gstflxdec.c: (flx_decode_delta_fli),
diff --git a/gst/matroska/matroska-mux.c b/gst/matroska/matroska-mux.c
index 78dcf960cf..84d59a967a 100644
--- a/gst/matroska/matroska-mux.c
+++ b/gst/matroska/matroska-mux.c
@@ -1324,6 +1324,7 @@ gst_matroska_mux_write_data (GstMatroskaMux * mux)
   guint64 cluster, blockgroup;
   gboolean write_duration;
   guint16 relative_timestamp;
+  guint64 block_duration;
 
   /* which stream to write from? */
   best = gst_matroska_mux_best_pad (mux);
@@ -1424,9 +1425,8 @@ gst_matroska_mux_write_data (GstMatroskaMux * mux)
 
   /* Check if the duration differs from the default duration. */
   write_duration = FALSE;
+  block_duration = GST_BUFFER_DURATION (buf);
   if (GST_BUFFER_DURATION_IS_VALID (buf)) {
-    guint64 block_duration = GST_BUFFER_DURATION (buf);
-
     if (block_duration != best->track->default_duration) {
       write_duration = TRUE;
     }
@@ -1460,8 +1460,6 @@ gst_matroska_mux_write_data (GstMatroskaMux * mux)
     gst_ebml_write_buffer (ebml, hdr);
     gst_ebml_write_buffer (ebml, buf);
     if (write_duration) {
-      guint64 block_duration = GST_BUFFER_DURATION (buf);
-
       gst_ebml_write_uint (ebml, GST_MATROSKA_ID_BLOCKDURATION,
           block_duration / mux->time_scale);
     }