diff --git a/util/mk1mf.pl b/util/mk1mf.pl
index 1f8b839e41cbefb38fee9047a2e4fd27a3eb2d7b..866629fe25be5593e9be21e90d7f941ef3a6720b 100755
--- a/util/mk1mf.pl
+++ b/util/mk1mf.pl
@@ -101,7 +101,7 @@ $out_def="out";
 $inc_def="outinc";
 $tmp_def="tmp";
 
-$mkdir="mkdir";
+$mkdir="-mkdir";
 
 ($ssl,$crypto)=("ssl","crypto");
 $ranlib="echo ranlib";