diff --git a/synapse/handlers/oidc.py b/synapse/handlers/oidc.py
index c9109c9e79..6450ec3145 100644
--- a/synapse/handlers/oidc.py
+++ b/synapse/handlers/oidc.py
@@ -731,6 +731,7 @@ class OidcProvider:
         }
 
         args = {
+            "client_id": self._client_auth.client_id,
             "grant_type": "authorization_code",
             "code": code,
             "redirect_uri": self._callback_url,