diff --git a/ChangeLog b/ChangeLog
index d8818585b..8d87e9182 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2010-09-08  Yves Blusseau  <blusseau@zetam.org>
+
+	* configure.ac: Define some useful variables.
+
 2010-09-08  Vladimir Serbinenko  <phcoder@gmail.com>
 
 	* grub-core/kern/ieee1275/cmain.c (grub_ieee1275_find_options): Set
diff --git a/configure.ac b/configure.ac
index 3a1a6da63..57b9bb3ac 100644
--- a/configure.ac
+++ b/configure.ac
@@ -176,6 +176,19 @@ AC_SUBST(host_kernel)
 AC_SUBST(target_cpu)
 AC_SUBST(platform)
 
+# Define default variables
+case "$host_os" in
+  netbsd* | openbsd*)
+        # Because /boot is used for the boot block in NetBSD and OpenBSD,
+        bootdirname=''      ;;
+  *)    bootdirname='boot'  ;;
+esac
+bootdirname=`echo "$bootdirname" | sed "$program_transform_name"`
+AC_SUBST(bootdirname)
+
+grubdirname=`echo "$PACKAGE" | sed "$program_transform_name"`
+AC_SUBST(grubdirname)
+
 #
 # Checks for build programs.
 #