diff --git a/winsup/doc/ChangeLog b/winsup/doc/ChangeLog
index 91e138226..bdfc1fd32 100644
--- a/winsup/doc/ChangeLog
+++ b/winsup/doc/ChangeLog
@@ -1,3 +1,8 @@
+2012-12-14  Corinna Vinschen  <corinna@vinschen.de>
+
+	* new-features.sgml (ov-new1.7.18): Add sparse change.
+	* pathnames.sgml (mount-table): Document sparse mount option.
+
 2012-12-06  Yaakov Selkowitz  <yselkowitz@users.sourceforge.net>
 
 	* new-features.sgml (ov-new1.7.18): New section. Document cfsetspeed.
diff --git a/winsup/doc/new-features.sgml b/winsup/doc/new-features.sgml
index b70a7e5d7..2c3e4707b 100644
--- a/winsup/doc/new-features.sgml
+++ b/winsup/doc/new-features.sgml
@@ -4,6 +4,11 @@
 
 <itemizedlist mark="bullet">
 
+<listitem><para>
+For performance reasons, Cygwin does not try to create sparse files
+automatically anymore, unless you use the new "sparse" mount option.
+</para></listitem>
+
 <listitem><para>
 New API: cfsetspeed.
 </para></listitem>
diff --git a/winsup/doc/pathnames.sgml b/winsup/doc/pathnames.sgml
index 3a4769e9e..774ad554d 100644
--- a/winsup/doc/pathnames.sgml
+++ b/winsup/doc/pathnames.sgml
@@ -117,6 +117,10 @@ posix=[0|1].  The meaning of the options is as follows.</para>
 	      (default for the cygdrive prefix).
   posix=1   - Switch on case sensitivity for paths under this mount point
 	      (default for all other mount points).
+  sparse    - Switch on support for sparse files.  This option only makes
+              sense on NTFS and then only if you really need sparse files.
+	      Cygwin does not try to create sparse files by default for
+	      performance reasons.
   text      - Files default to CRLF text mode line endings.
   user      - Mount is a user mount.
 </screen>