diff --git a/xdk/oauth2_auth.py b/xdk/oauth2_auth.py
index 228c13f..b809eb6 100644
--- a/xdk/oauth2_auth.py
+++ b/xdk/oauth2_auth.py
@@ -224,7 +224,7 @@ def refresh_token(self) -> Dict[str, Any]:
             raise ValueError("No token to refresh")
         refresh_url = f"{self.base_url}/2/oauth2/token"
         self.token = self.oauth2_session.refresh_token(
-            refresh_url, client_id=self.client_id, client_secret=self.client_secret
+            refresh_url, auth=HTTPBasicAuth(self.client_id, self.client_secret)
         )
         return self.token