diff --git a/lib/Saml2/Auth.php b/lib/Saml2/Auth.php
index c8a1c6f0..bb882cd0 100644
--- a/lib/Saml2/Auth.php
+++ b/lib/Saml2/Auth.php
@@ -246,6 +246,7 @@ public function processResponse($requestId = null)
      * @param bool        $stay                         True if we want to stay (returns the url string) False to redirect
      *
      * @return string|null
+     * @phpstan-return ($stay is true ? string : never)
      *
      * @throws OneLogin_Saml2_Error
      */
@@ -498,6 +499,7 @@ public function getAttributeWithFriendlyName($friendlyName)
      * @param string $nameIdValueReq Indicates to the IdP the subject that should be authenticated
      *
      * @return string|null If $stay is True, it return a string with the SLO URL + LogoutRequest + parameters
+     * @phpstan-return ($stay is true ? string : never)
      *
      * @throws OneLogin_Saml2_Error
      */
@@ -540,6 +542,7 @@ public function login($returnTo = null, $parameters = array(), $forceAuthn = fal
      * @param string|null $nameIdNameQualifier The NameID NameQualifier will be set in the LogoutRequest.
      *
      * @return string|null If $stay is True, it return a string with the SLO URL + LogoutRequest + parameters
+     * @phpstan-return ($stay is true ? string : never)
      *
      * @throws OneLogin_Saml2_Error
      */
diff --git a/lib/Saml2/Utils.php b/lib/Saml2/Utils.php
index 24ecbd58..1a7f85f3 100644
--- a/lib/Saml2/Utils.php
+++ b/lib/Saml2/Utils.php
@@ -300,6 +300,7 @@ public static function getStringBetween($str, $start, $end)
      * @param bool         $stay       True if we want to stay (returns the url string) False to redirect
      *
      * @return string|null $url
+     * @phpstan-return ($stay is true ? string : never)
      *
      * @throws OneLogin_Saml2_Error
      */