diff --git a/webnotes/sessions.py b/webnotes/sessions.py
index ebab2bb4e6..f541d54fc0 100644
--- a/webnotes/sessions.py
+++ b/webnotes/sessions.py
@@ -202,7 +202,8 @@ class Session:
 	def update(self):
 		"""extend session expiry"""
 		self.data['data']['last_updated'] = webnotes.utils.now()
-		self.data['data']['lang'] = webnotes.lang
+		self.data['data']['lang'] = unicode(webnotes.lang)
+
 
 		# update session in db
 		time_diff = None