--- configure.ac.orig   2009-01-22 15:39:57.000000000 +0100
+++ configure.ac        2009-01-22 15:40:50.000000000 +0100
@@ -244,7 +244,7 @@
 
 
 CFLAGS="$CFLAGS -Wall"
-CPPFLAGS="$CPPFLAGS -I\$(top_srcdir) -I\$(top_srcdir)/include"
+CPPFLAGS="-I\$(top_srcdir) -I\$(top_srcdir)/include $CPPFLAGS"
 
 
 # check for lex/flex
--- configure.orig      2009-01-22 15:44:41.000000000 +0100
+++ configure   2009-01-22 15:46:01.000000000 +0100
@@ -9269,7 +9269,7 @@
 
 
 CFLAGS="$CFLAGS -Wall"
-CPPFLAGS="$CPPFLAGS -I\$(top_srcdir) -I\$(top_srcdir)/include"
+CPPFLAGS="-I\$(top_srcdir) -I\$(top_srcdir)/include $CPPFLAGS"
 
 
 # check for lex/flex