diff --git a/index.d.ts b/index.d.ts
index 4650b2e6..ff764946 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -419,6 +419,13 @@ interface SessionConfigParams {
    */
   absoluteDuration?: boolean | number;
 
+  /**
+   * Configuration parameters used for the session cookie and transient cookies.
+   */
+  cookie?: CookieConfigParams;
+}
+
+interface CookieConfigParams {
   /**
    * Domain name for the cookie.
    * Passed to the [Response cookie](https://expressjs.com/en/api.html#res.cookie) as `domain`