diff --git a/packages/isomorphic-unfetch/index.js b/packages/isomorphic-unfetch/index.js
index d78c3d8..dacdb66 100644
--- a/packages/isomorphic-unfetch/index.js
+++ b/packages/isomorphic-unfetch/index.js
@@ -1,6 +1,6 @@
 function r(m){return m && m.default || m;}
 module.exports = global.fetch = global.fetch || (
 	typeof process=='undefined' ? r(require('unfetch')) : (function(url, opts) {
-		return r(require('node-fetch'))(url.replace(/^\/\//g,'https://'), opts);
+		return r(require('node-fetch'))(String(url).replace(/^\/\//g,'https://'), opts);
 	})
 );