Index: ax_boost_base.m4
===================================================================
--- ax_boost_base.m4	(revision 3292)
+++ ax_boost_base.m4	(revision 3293)
@@ -61,7 +61,7 @@
         AS_HELP_STRING([--with-boost-libdir=LIB_DIR],
         [Force given directory for boost libraries. Note that this will overwrite library path detection, so use this parameter only if default library detection fails and you know exactly where your boost libraries are located.]),
         [
-        if test -d $withval
+        if test -d "$withval"
         then
                 ac_boost_lib_path="$withval"
         else