Oops. Close the file.
diff --git a/util/mk1mf.pl b/util/mk1mf.pl
index 90943de..355143b 100755
--- a/util/mk1mf.pl
+++ b/util/mk1mf.pl
@@ -15,6 +15,7 @@
     $options=$1 if (/^OPTIONS=(.*)$/);
     $INSTALLTOP=$1 if (/^INSTALLTOP=(.*$)/);
 }
+close(IN);
 
 die "Makefile.ssl is not the toplevel Makefile!\n" if $ssl_version eq "";