Recognise new option.
diff --git a/util/mk1mf.pl b/util/mk1mf.pl
index d639fba..e27e81b 100755
--- a/util/mk1mf.pl
+++ b/util/mk1mf.pl
@@ -1352,7 +1352,7 @@
 		"no-cms" => \$no_cms,
 		"no-jpake" => \$no_jpake,
 		"no-ec2m" => \$no_ec2m,
-		"no-ec-nistp224-64-gcc-128" => 0,
+		"no-ec_nistp_64_gcc_128" => 0,
 		"no-err" => \$no_err,
 		"no-sock" => \$no_sock,
 		"no-krb5" => \$no_krb5,