diff --git a/lib/sessionmanager.js b/lib/sessionmanager.js
index f4123def..81b59b1d 100644
--- a/lib/sessionmanager.js
+++ b/lib/sessionmanager.js
@@ -1,3 +1,5 @@
+var merge = require('utils-merge');
+
 function SessionManager(options, serializeUser) {
   if (typeof options == 'function') {
     serializeUser = options;
@@ -33,7 +35,7 @@ SessionManager.prototype.logIn = function(req, user, options, cb) {
         return cb(err);
       }
       if (options.keepSessionInfo) {
-        Object.assign(req.session, prevSession);
+        merge(req.session, prevSession);
       }
       if (!req.session[self._key]) {
         req.session[self._key] = {};
@@ -83,7 +85,7 @@ SessionManager.prototype.logOut = function(req, options, cb) {
         return cb(err);
       }
       if (options.keepSessionInfo) {
-        Object.assign(req.session, prevSession);
+        merge(req.session, prevSession);
       }
       cb();
     });
diff --git a/package.json b/package.json
index 53cbd220..00398a85 100644
--- a/package.json
+++ b/package.json
@@ -36,7 +36,8 @@
   "main": "./lib",
   "dependencies": {
     "passport-strategy": "1.x.x",
-    "pause": "0.0.1"
+    "pause": "0.0.1",
+    "utils-merge": "^1.0.1"
   },
   "devDependencies": {
     "make-node": "0.3.x",