diff --git a/composer.json b/composer.json
index b42461a1..56f52d3d 100644
--- a/composer.json
+++ b/composer.json
@@ -38,7 +38,7 @@
         "psalm/plugin-phpunit":                   "^0.17.0",
         "roave/infection-static-analysis-plugin": "^1.22.0",
         "squizlabs/php_codesniffer":              "^3.7.1",
-        "vimeo/psalm":                            "^4.26.0"
+        "vimeo/psalm":                            "^4.27.0"
     },
     "config": {
         "allow-plugins": {
diff --git a/composer.lock b/composer.lock
index f05b6657..27fa41b9 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "c2495095fe742b7ea6ccd9d560f6895d",
+    "content-hash": "57f23d47b480bc21c8b59163990ebaa1",
     "packages": [
         {
             "name": "dflydev/fig-cookies",
@@ -5502,16 +5502,16 @@
         },
         {
             "name": "vimeo/psalm",
-            "version": "4.26.0",
+            "version": "4.27.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/vimeo/psalm.git",
-                "reference": "6998fabb2bf528b65777bf9941920888d23c03ac"
+                "reference": "faf106e717c37b8c81721845dba9de3d8deed8ff"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/vimeo/psalm/zipball/6998fabb2bf528b65777bf9941920888d23c03ac",
-                "reference": "6998fabb2bf528b65777bf9941920888d23c03ac",
+                "url": "https://api.github.com/repos/vimeo/psalm/zipball/faf106e717c37b8c81721845dba9de3d8deed8ff",
+                "reference": "faf106e717c37b8c81721845dba9de3d8deed8ff",
                 "shasum": ""
             },
             "require": {
@@ -5603,9 +5603,9 @@
             ],
             "support": {
                 "issues": "https://github.com/vimeo/psalm/issues",
-                "source": "https://github.com/vimeo/psalm/tree/4.26.0"
+                "source": "https://github.com/vimeo/psalm/tree/4.27.0"
             },
-            "time": "2022-07-31T13:10:26+00:00"
+            "time": "2022-08-31T13:47:09+00:00"
         },
         {
             "name": "webmozart/assert",
diff --git a/src/Storageless/Http/SessionMiddleware.php b/src/Storageless/Http/SessionMiddleware.php
index 556f3261..2f239f96 100644
--- a/src/Storageless/Http/SessionMiddleware.php
+++ b/src/Storageless/Http/SessionMiddleware.php
@@ -46,6 +46,7 @@
 use PSR7Sessions\Storageless\Session\SessionInterface;
 use stdClass;
 
+use function assert;
 use function date_default_timezone_get;
 use function sprintf;
 
@@ -55,9 +56,7 @@ final class SessionMiddleware implements MiddlewareInterface
     public const SESSION_ATTRIBUTE    = 'session';
     public const DEFAULT_COOKIE       = '__Secure-slsession';
     public const DEFAULT_REFRESH_TIME = 60;
-
     private Configuration $config;
-
     private SetCookie $defaultCookie;
 
     public function __construct(
@@ -209,8 +208,12 @@ private function appendToken(SessionInterface $sessionContainer, Response $respo
 
     private function shouldTokenBeRefreshed(Token|null $token): bool
     {
+        $refreshTime = $this->clock->now()->sub(new DateInterval(sprintf('PT%sS', $this->refreshTime)));
+
+        assert($refreshTime !== false);
+
         return $token !== null
-            && $token->hasBeenIssuedBefore($this->clock->now()->sub(new DateInterval(sprintf('PT%sS', $this->refreshTime))));
+            && $token->hasBeenIssuedBefore($refreshTime);
     }
 
     /** @throws BadMethodCallException */
@@ -237,6 +240,8 @@ private function getExpirationCookie(): SetCookie
     {
         $expirationDate = $this->clock->now()->modify('-30 days');
 
+        assert($expirationDate !== false);
+
         return $this
             ->defaultCookie
             ->withValue(null)