diff --git a/mithril.js b/mithril.js
index a2bc57d9..7c8b8e35 100644
--- a/mithril.js
+++ b/mithril.js
@@ -117,6 +117,7 @@ var m = (function app(window, undefined) {
 				if (type.call(data[i]) === ARRAY) {
 					data = data.concat.apply([], data);
 					i-- //check current index again and flatten until there are no more nested arrays at that index
+					len = data.length
 				}
 			}