diff --git a/ChangeLog b/ChangeLog
index 287f5bef7..dd2381f12 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2011-02-17  Moritz Bunkus  <moritz@bunkus.org>
+
+	* mkvmerge: enhancement: HD-DVD subtitles are recognized as being
+	an unsupported file format. This makes the error message presented
+	to the user a bit clearer. Fix for bug 600.
+
 2011-02-15  Moritz Bunkus  <moritz@bunkus.org>
 
 	* build: Boost 1.36.0 or newer is required (up from 1.34.0). Also
diff --git a/src/common/file_types.h b/src/common/file_types.h
index bed751c6e..c7bd5f656 100644
--- a/src/common/file_types.h
+++ b/src/common/file_types.h
@@ -32,6 +32,7 @@ enum file_type_e {
   FILE_TYPE_DTS,
   FILE_TYPE_FLAC,
   FILE_TYPE_FLV,
+  FILE_TYPE_HDSUB,
   FILE_TYPE_IVF,
   FILE_TYPE_MATROSKA,
   FILE_TYPE_MICRODVD,
diff --git a/src/common/hdsub.h b/src/common/hdsub.h
new file mode 100644
index 000000000..f3298d20e
--- /dev/null
+++ b/src/common/hdsub.h
@@ -0,0 +1,22 @@
+/*
+   mkvmerge -- utility for splicing together matroska files
+   from component media subtypes
+
+   Distributed under the GPL
+   see the file COPYING for details
+   or visit http://www.gnu.org/copyleft/gpl.html
+
+   definitions and helper functions for PGS/SUP subtitles
+
+   Written by Moritz Bunkus <moritz@bunkus.org>.
+*/
+
+#ifndef __MTX_COMMON_PGSSUP_H
+#define __MTX_COMMON_PGSSUP_H
+
+#include "common/os.h"
+
+#define HDSUB_FILE_MAGIC 0x5350 // "SP" big endian
+
+#endif  // __MTX_COMMON_HDSUB_H
+
diff --git a/src/input/r_hdsub.cpp b/src/input/r_hdsub.cpp
new file mode 100644
index 000000000..85ad8c140
--- /dev/null
+++ b/src/input/r_hdsub.cpp
@@ -0,0 +1,45 @@
+/*
+   mkvmerge -- utility for splicing together matroska files
+   from component media subtypes
+
+   Distributed under the GPL
+   see the file COPYING for details
+   or visit http://www.gnu.org/copyleft/gpl.html
+
+   HDSUB demultiplexer module
+
+   Written by Moritz Bunkus <moritz@bunkus.org>.
+*/
+
+#include "common/common_pch.h"
+
+#include "common/endian.h"
+#include "common/hdsub.h"
+#include "input/r_hdsub.h"
+
+int
+hdsub_reader_c::probe_file(mm_io_c *io,
+                         uint64_t size) {
+  try {
+    if (2 > size)
+      return 0;
+
+    unsigned char buf[2];
+
+    io->setFilePointer(0, seek_beginning);
+    if (io->read(buf, 2) != 2)
+      return 0;
+    io->setFilePointer(0, seek_beginning);
+
+    if (HDSUB_FILE_MAGIC == get_uint16_be(buf)) {
+      id_result_container_unsupported(io->get_file_name(), "HD-DVD sub");
+      // Never reached:
+      return 1;
+    }
+
+    return 0;
+
+  } catch (...) {
+    return 0;
+  }
+}
diff --git a/src/input/r_hdsub.h b/src/input/r_hdsub.h
new file mode 100644
index 000000000..64996d8c8
--- /dev/null
+++ b/src/input/r_hdsub.h
@@ -0,0 +1,32 @@
+/*
+   mkvmerge -- utility for splicing together matroska files
+   from component media subtypes
+
+   Distributed under the GPL
+   see the file COPYING for details
+   or visit http://www.gnu.org/copyleft/gpl.html
+
+   class definitions for the HDSUB demultiplexer module
+
+   Written by Moritz Bunkus <moritz@bunkus.org>.
+*/
+
+#ifndef __R_HDSUB_H
+#define __R_HDSUB_H
+
+#include "common/common_pch.h"
+
+#include <stdio.h>
+
+#include "common/error.h"
+#include "common/mm_io.h"
+#include "merge/pr_generic.h"
+
+class hdsub_reader_c: public generic_reader_c {
+public:
+  hdsub_reader_c(track_info_c &n_ti): generic_reader_c(n_ti) { };
+
+  static int probe_file(mm_io_c *in, uint64_t size);
+};
+
+#endif // __R_HDSUB_H
diff --git a/src/merge/output_control.cpp b/src/merge/output_control.cpp
index 6201e47ef..358af9191 100644
--- a/src/merge/output_control.cpp
+++ b/src/merge/output_control.cpp
@@ -84,6 +84,7 @@
 #include "input/r_dts.h"
 #include "input/r_flac.h"
 #include "input/r_flv.h"
+#include "input/r_hdsub.h"
 #include "input/r_ivf.h"
 #include "input/r_matroska.h"
 #include "input/r_mp3.h"
@@ -315,6 +316,8 @@ get_file_type(filelist_t &file) {
     type = FILE_TYPE_CDXA;
   else if (flv_reader_c::probe_file(io, size))
     type = FILE_TYPE_FLV;
+  else if (hdsub_reader_c::probe_file(io, size))
+    type = FILE_TYPE_HDSUB;
   // File types that can be detected unambiguously
   else if (avi_reader_c::probe_file(io, size))
     type = FILE_TYPE_AVI;