diff --git a/lib/system/has-flag.js b/lib/system/has-flag.js
index df0f8c9..0ebdbf5 100644
--- a/lib/system/has-flag.js
+++ b/lib/system/has-flag.js
@@ -14,8 +14,10 @@ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLI
 
 module.exports = function (flag, argv) {
 	argv = argv || process.argv;
-	var prefix = flag.startsWith('-') ? '' : flag.length === 1 ? '-' : '--';
-	var pos = argv.indexOf(prefix + flag);
+
 	var terminatorPos = argv.indexOf('--');
+	var prefix = /^-{1,2}/.test(flag) ? '' : '--';
+	var pos = argv.indexOf(prefix + flag);
+
 	return pos !== -1 && (terminatorPos === -1 ? true : pos < terminatorPos);
 };