diff --git a/fitbit/api.py b/fitbit/api.py
index ba9d037..1b458b1 100644
--- a/fitbit/api.py
+++ b/fitbit/api.py
@@ -143,6 +143,7 @@ def fetch_access_token(self, code, redirect_uri=None):
             self.access_token_url,
             username=self.client_id,
             password=self.client_secret,
+            client_secret=self.client_secret,
             code=code)
 
     def refresh_token(self):