diff --git a/configure.ac b/configure.ac
index 673f4179..65c25155 100644
--- a/configure.ac
+++ b/configure.ac
@@ -15,7 +15,7 @@ CARES_CHECK_OPTION_OPTIMIZE
 CARES_CHECK_OPTION_WARNINGS
 CARES_CHECK_OPTION_CURLDEBUG
 
-CARES_CHECK_PATH_SEPARATOR
+CARES_CHECK_PATH_SEPARATOR_REQUIRED
 
 dnl SED is mandatory for configure process and libtool.
 dnl Set it now, allowing it to be changed later.
diff --git a/m4/cares-system.m4 b/m4/cares-system.m4
index 39b3c859..f0adc897 100644
--- a/m4/cares-system.m4
+++ b/m4/cares-system.m4
@@ -1,7 +1,7 @@
 #***************************************************************************
 # $Id$
 #
-# Copyright (C) 2008 by Daniel Stenberg et al
+# Copyright (C) 2008 - 2009 by Daniel Stenberg et al
 #
 # Permission to use, copy, modify, and distribute this software and its
 # documentation for any purpose and without fee is hereby granted, provided
@@ -16,7 +16,7 @@
 #***************************************************************************
 
 # File version for 'aclocal' use. Keep it a single number.
-# serial 2
+# serial 3
 
 
 dnl CARES_CHECK_PATH_SEPARATOR
@@ -72,3 +72,12 @@ AC_DEFUN([CARES_CHECK_PATH_SEPARATOR], [
 ])
 
 
+dnl CARES_CHECK_PATH_SEPARATOR_REQUIRED
+dnl -------------------------------------------------
+dnl Use this to ensure that the path separator check
+dnl macro is only expanded and included once.
+
+AC_DEFUN([CARES_CHECK_PATH_SEPARATOR_REQUIRED], [
+  AC_REQUIRE([CARES_CHECK_PATH_SEPARATOR])dnl
+])
+