diff --git a/mpesa/services.py b/mpesa/services.py
index 6b04f1d..e0f755c 100644
--- a/mpesa/services.py
+++ b/mpesa/services.py
@@ -62,7 +62,7 @@ def get_access_token(self):
 
     def _generate_password(self, timestamp):
         string = self.shortcode + self.passphrase + timestamp
-        return bytes(string, 'utf-8')
+        return string.decode('utf-8')
 
     def process_request(self, phone_number=None, amount=None,
                         callback_url=None, reference="", description=""):