diff --git a/m4/acinclude.m4 b/m4/acinclude.m4
index 0c71173933f8c7a9f6b95a272b97b97df24f99ee..deebd2bf81ae846e0f7908c94394b53193dc93da 100644
--- a/m4/acinclude.m4
+++ b/m4/acinclude.m4
@@ -1,6 +1,15 @@
+dnl as-ac-expand.m4 0.2.0                                   -*- autoconf -*-
+dnl autostars m4 macro for expanding directories using configure's prefix
+
+dnl (C) 2003, 2004, 2005 Thomas Vander Stichele <thomas at apestaart dot org>
+
+dnl Copying and distribution of this file, with or without modification,
+dnl are permitted in any medium without royalty provided the copyright
+dnl notice and this notice are preserved.
+
 dnl AS_AC_EXPAND(VAR, CONFIGURE_VAR)
-dnl
-dnl example
+
+dnl example:
 dnl AS_AC_EXPAND(SYSCONFDIR, $sysconfdir)
 dnl will set SYSCONFDIR to /usr/local/etc if prefix=/usr/local
 
@@ -15,7 +24,7 @@ AC_DEFUN([AS_AC_EXPAND],
 
   dnl if no prefix given, then use /usr/local, the default prefix
   if test "x$prefix" = "xNONE"; then
-    prefix=$ac_default_prefix
+    prefix="$ac_default_prefix"
   fi
   dnl if no exec_prefix given, then use prefix
   if test "x$exec_prefix" = "xNONE"; then
@@ -26,7 +35,7 @@ AC_DEFUN([AS_AC_EXPAND],
   dnl loop until it doesn't change anymore
   while true; do
     new_full_var="`eval echo $full_var`"
-    if test "x$new_full_var"="x$full_var"; then break; fi
+    if test "x$new_full_var" = "x$full_var"; then break; fi
     full_var=$new_full_var
   done