diff --git a/lib/flash.js b/lib/flash.js
index a278bc1..0fffd90 100644
--- a/lib/flash.js
+++ b/lib/flash.js
@@ -58,7 +58,7 @@ module.exports = function flash(options) {
  */
 function _flash(type, msg) {
   if (this.session === undefined) throw Error('req.flash() requires sessions');
-  var msgs = this.session.flash = this.session.flash || {};
+  var msgs = this.session.flash || {};
   if (type && msg) {
     // util.format is available in Node.js 0.6+
     if (arguments.length > 2 && format) {