diff --git a/frappeclient/frappeclient.py b/frappeclient/frappeclient.py
index f368515..445edc5 100644
--- a/frappeclient/frappeclient.py
+++ b/frappeclient/frappeclient.py
@@ -62,7 +62,7 @@ def login(self, username, password):
 			raise AuthError
 
 	def authenticate(self, api_key, api_secret):
-		token = b64encode('{}:{}'.format(api_key, api_secret))
+		token = b64encode('{}:{}'.format(api_key, api_secret).encode("utf-8")).decode("utf-8")
 		auth_header = {'Authorization': 'Basic {}'.format(token)}
 		self.session.headers.update(auth_header)