diff --git a/winsup/doc/ChangeLog b/winsup/doc/ChangeLog
index 3dd272f63..44720a021 100644
--- a/winsup/doc/ChangeLog
+++ b/winsup/doc/ChangeLog
@@ -1,3 +1,7 @@
+2005-04-19  Corinna Vinschen  <corinna@vinschen.de>
+
+	* cygwinenv.sgml: Mention that check_case is deprecated.
+
 2005-04-16  Corinna Vinschen  <corinna@vinschen.de>
 
 	* cygwinenv.sgml: Add new words for (no)traverse option.
diff --git a/winsup/doc/cygwinenv.sgml b/winsup/doc/cygwinenv.sgml
index 782c28959..744927554 100644
--- a/winsup/doc/cygwinenv.sgml
+++ b/winsup/doc/cygwinenv.sgml
@@ -22,7 +22,10 @@ pipe to binary by default.
 </para>
 </listitem>
 <listitem>
-<para><envar>check_case:level</envar> - Controls the behavior of
+<para><envar>check_case:level</envar> - THIS OPTION IS DEPRECATED.
+Don't use it unless you know what you're doing and don't see any way
+around it.  And even then, this option is error prone, slows down Cygwin
+and not well maintained.  This option controls the behavior of
 Cygwin when a user tries to open or create a file using a case different from
 the case of the path as saved on the disk.
 <literal>level</literal> is one of <literal>relaxed</literal>,