Add reference to the Solaris bug.
diff --git a/ChangeLog b/ChangeLog
index a9b8166..645c1b3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2009-11-22  Bruno Haible  <bruno@clisp.org>
+
+	* tests/check-subst: Add reference to the Solaris printf bug.
+	Reported by Dagobert Michelsen <dagobert@familie-michelsen.de>.
+
 2009-09-01  Bruno Haible  <bruno@clisp.org>
 
 	* README.woe32: Put the -mno-cygwin option into CC and CXX.
diff --git a/tests/check-subst b/tests/check-subst
index c17b11a..67339a9 100755
--- a/tests/check-subst
+++ b/tests/check-subst
@@ -52,6 +52,7 @@
 EOF
 $iconv --byte-subst='<0x%010000x>' -f ASCII -t ASCII < tmp-in > tmp-out
 # This printf command crashes on Solaris 10.
+# See <http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6550204>.
 if printf 'B<0x%010000x><0x%010000x>se B<0x%010000x><0x%010000x>bchen\n' 0xC3 0xB6 0xC3 0xBC > tmp-ok 2>/dev/null; then
   cmp tmp-out tmp-ok
 fi
@@ -97,6 +98,7 @@
 EOF
 $iconv --unicode-subst='<U+%010000X>' -f UTF-8 -t ASCII < tmp-in > tmp-out
 # This printf command crashes on Solaris 10.
+# See <http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6550204>.
 if printf 'B<U+%010000X>se B<U+%010000X>bchen\n' 0x00F6 0x00FC > tmp-ok 2>/dev/null; then
   cmp tmp-out tmp-ok
 fi
@@ -106,6 +108,7 @@
 EOF
 $iconv --byte-subst='<0x%010000x>' -f ASCII -t ASCII < tmp-in > tmp-out
 # This printf command crashes on Solaris 10.
+# See <http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6550204>.
 if printf 'B<0x%010000x><0x%010000x>se B<0x%010000x><0x%010000x>bchen\n' 0xC3 0xB6 0xC3 0xBC > tmp-ok 2>/dev/null; then
   cmp tmp-out tmp-ok
 fi