diff --git a/src/Token/AccessTokenInterface.php b/src/Token/AccessTokenInterface.php
index cec37f61..c5f13350 100644
--- a/src/Token/AccessTokenInterface.php
+++ b/src/Token/AccessTokenInterface.php
@@ -34,7 +34,7 @@ public function getToken();
     public function getRefreshToken();
 
     /**
-     * Returns the expiration timestamp, if defined.
+     * Returns the expiration timestamp in seconds, if defined.
      *
      * @return integer|null
      */