diff --git a/README.md b/README.md
index 4fb3d3a..9353dec 100644
--- a/README.md
+++ b/README.md
@@ -164,7 +164,6 @@ Example (in `metadata/saml20-idp-hosted.php`):
             // Optional:
             'warnDaysBefore' => 14,
             'originalUrlParam' => 'originalurl',
-            'dateFormat' => 'm.d.Y', // Use PHP's date syntax.
             'loggerClass' => '\\Sil\\Psr3Adapters\\Psr3SamlLogger',
         ],
 
@@ -187,11 +186,6 @@ their password.
 The `warnDaysBefore` parameter should be an integer representing how many days
 before the expiry date the "about to expire" warning will be shown to the user.
 
-The `dateFormat` parameter specifies how you want the date to be formatted,
-using PHP `date()` syntax. See <http://php.net/manual/en/function.date.php>.
-
-The `originalUrlParam` parameter is not used.
-
 The `loggerClass` parameter specifies the name of a PSR-3 compatible class that
 can be autoloaded, to use as the logger within ExpiryDate.
 
diff --git a/modules/expirychecker/src/Auth/Process/ExpiryDate.php b/modules/expirychecker/src/Auth/Process/ExpiryDate.php
index 3efd9e6..4a91002 100644
--- a/modules/expirychecker/src/Auth/Process/ExpiryDate.php
+++ b/modules/expirychecker/src/Auth/Process/ExpiryDate.php
@@ -32,7 +32,6 @@ class ExpiryDate extends ProcessingFilter
     private string|null $accountNameAttr = null;
     private string $employeeIdAttr = 'employeeNumber';
     private string|null $expiryDateAttr = null;
-    private string $dateFormat = 'Y-m-d';
 
     protected LoggerInterface $logger;
 
@@ -70,10 +69,6 @@ public function __construct(array $config, mixed $reserved)
                 Validator::STRING,
                 Validator::NOT_EMPTY,
             ],
-            'dateFormat' => [
-                Validator::STRING,
-                Validator::NOT_EMPTY,
-            ],
         ]);
     }