diff --git a/index.d.ts b/index.d.ts
index a8a58c41..2bb07416 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -166,6 +166,8 @@ export interface OidcClientSettings {
   MetadataServiceCtor?: MetadataServiceCtor;
   /** An object containing additional query string parameters to be including in the authorization request */
   extraQueryParams?: Record<string, any>;
+  /** An object containing additional string parameters to be including in the token request */
+  extraTokenParams?: Record<string, any>;
 }
 
 export class UserManager extends OidcClient {