--- a/m4/ax_check_zlib.m4	2012-07-17 21:43:37.000000000 +1000
+++ b/m4/ax_check_zlib.m4	2012-07-17 21:43:47.000000000 +1000
@@ -72,10 +72,10 @@
 #
 [AC_MSG_CHECKING(if zlib is wanted)
 zlib_places="/usr/local /usr /opt/local /sw"
-AC_ARG_WITH(zlib,
-[  --with-zlib=DIR root directory path of zlib installation [defaults to
-                    /usr/local or /usr if not found in /usr/local]
-  --without-zlib to disable zlib usage completely],
+AC_ARG_WITH([zlib],
+[  --with-zlib=DIR         root directory path of zlib installation @<:@defaults to
+                          /usr/local or /usr if not found in /usr/local@:>@
+  --without-zlib          to disable zlib usage completely],
 [if test "$withval" != no ; then
   AC_MSG_RESULT(yes)
   if test -d "$withval"