diff --git a/modules/silauth/lib/Auth/Source/auth/Authenticator.php b/modules/silauth/lib/Auth/Source/auth/Authenticator.php
index 2e91ed7e..fd084978 100644
--- a/modules/silauth/lib/Auth/Source/auth/Authenticator.php
+++ b/modules/silauth/lib/Auth/Source/auth/Authenticator.php
@@ -274,7 +274,7 @@ protected function isBlockedByRateLimit(string $username, array $ipAddresses): b
                FailedLoginIpAddress::isRateLimitBlockingAnyOfThese($ipAddresses);
     }
     
-    public static function isCaptchaRequired(string $username, array $ipAddresses): bool
+    public static function isCaptchaRequired(?string $username, array $ipAddresses): bool
     {
         return FailedLoginUsername::isCaptchaRequiredFor($username) ||
                FailedLoginIpAddress::isCaptchaRequiredForAnyOfThese($ipAddresses);
diff --git a/modules/silauth/lib/Auth/Source/models/FailedLoginUsername.php b/modules/silauth/lib/Auth/Source/models/FailedLoginUsername.php
index 26615487..4b67faac 100644
--- a/modules/silauth/lib/Auth/Source/models/FailedLoginUsername.php
+++ b/modules/silauth/lib/Auth/Source/models/FailedLoginUsername.php
@@ -108,7 +108,7 @@ public static function isRateLimitBlocking(string $username): bool
         return ($secondsUntilUnblocked > 0);
     }
     
-    public static function isCaptchaRequiredFor(string $username): bool
+    public static function isCaptchaRequiredFor(?string $username): bool
     {
         if (empty($username)) {
             return false;