diff --git a/ChangeLog b/ChangeLog
index 4257c27306..1151588114 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2005-02-07  Lars Gullik Bjonnes  <larsbj@gullik.net>
+
+	* configure.ac (AH_BOTTOM): make BOOST_POSIX be defined for cygwin 
+
 2005-02-02  Jean-Marc Lasgouttes  <lasgouttes@lyx.org>
 
 	* configure.ac: if the prefix contains space, replace it with
@@ -7,7 +11,7 @@
 
 2005-01-27  Lars Gullik Bjonnes  <larsbj@gullik.net>
 
-	* configure.ac: add src/support/tests/Makefile 
+	* configure.ac: add src/support/tests/Makefile
 
 2005-01-21  Jean-Marc Lasgouttes  <lasgouttes@lyx.org>
 
diff --git a/configure.ac b/configure.ac
index bc7b014ce2..af1a2c5273 100644
--- a/configure.ac
+++ b/configure.ac
@@ -231,7 +231,7 @@ test "x$prefix" = xNONE && prefix=$default_prefix
 test "x$exec_prefix" = xNONE && exec_prefix='${prefix}'
 if echo $prefix |grep ' ' >/dev/null 2>/dev/null ; then
   LYX_WARNING([The installation prefix \"${prefix}\" contains a space, which
-   causes problems with the Makefiles. The installation will be done in 
+   causes problems with the Makefiles. The installation will be done in
    directory \"`pwd`/installprefix\" instead. Please move its contents to
    the right place after installation.])
   prefix=`pwd`/installprefix
@@ -389,6 +389,10 @@ int mkstemp(char*);
 #define BOOST_NO_WREGEX 1
 #define BOOST_NO_WSTRING 1
 
+#ifdef __CYGWIN__
+#define BOOST_POSIX 1
+#endif
+
 #endif
 ])