diff --git a/index.js b/index.js
index 61615f1..3e3a656 100644
--- a/index.js
+++ b/index.js
@@ -2,9 +2,10 @@
 
 var path = require('path');
 var isglob = require('is-glob');
+var pathDirname = require('path-dirname');
 
 module.exports = function globParent(str) {
 	str += 'a'; // preserves full path in case of trailing path separator
-	do {str = path.dirname(str)} while (isglob(str));
+	do {str = pathDirname.posix(str)} while (isglob(str));
 	return str;
 };
diff --git a/package.json b/package.json
index 86cfb24..bb750a6 100644
--- a/package.json
+++ b/package.json
@@ -28,7 +28,8 @@
   },
   "homepage": "https://github.com/es128/glob-parent",
   "dependencies": {
-    "is-glob": "^3.1.0"
+    "is-glob": "^3.1.0",
+    "path-dirname": "^1.0.0"
   },
   "devDependencies": {
     "coveralls": "^2.11.2",