--- a/Makefile.PL	2006-10-01 21:28:25.000000000 +0000
+++ b/Makefile.PL	2014-01-23 15:40:56.784222851 +0000
@@ -4,7 +4,8 @@
 use ExtUtils::MakeMaker;
 use Config;
 
-unless ($Config{useperlio} eq 'define' and $Config{usesfio} eq 'false') {
+unless ($Config{useperlio} eq 'define' and
+	(defined($Config{usesfio}) ? $Config{usesfio} : 'false') eq 'false') {
   die <<BARF;
 You need perl 5.8.0 or later, configured to use perlio (and not to use sfio)
 BARF