diff --git a/src/TaxisLibrary/taxis_client.py b/src/TaxisLibrary/taxis_client.py
index a4ab2ac..88bb867 100644
--- a/src/TaxisLibrary/taxis_client.py
+++ b/src/TaxisLibrary/taxis_client.py
@@ -255,7 +255,7 @@ class TaxisClient:
             "client_id": client_id,
             "client_secret": client_secret
         }
-        result = await self._request("POST", "/auth/login", json_data=data)
+        result = await self._request("POST", "/auth/login", data=data)
         self.api_key = result["api_key"]
         self.session.headers.update({"Authorization": f"Bearer {self.api_key}"})
         return ApiKeyOut(**result)