diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 169c282..8fb0abd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,11 +9,11 @@ jobs:
     steps:
       - uses: shivammathur/setup-php@v2
         with:
-          php-version: 7.4
+          php-version: 8.1
       - uses: actions/checkout@v3
-      - uses: php-actions/composer@v5
+      - uses: php-actions/composer@v6
       - name: Run PHPStan Static Analysis
-        uses: php-actions/phpstan@master
+        uses: php-actions/phpstan@v3
         with:
           memory_limit: 512M
           path: src/Pipit/
diff --git a/phpstan.dist b/phpstan.dist
index c631730..f8b774a 100644
--- a/phpstan.dist
+++ b/phpstan.dist
@@ -1,6 +1,6 @@
 parameters:
     paths:
         - src/Pipit
-    level: 8
+    level: 9
     bootstrapFiles:
         - ./phpstan/constants.php
diff --git a/src/Pipit/Classes/Data/ResultsPage.php b/src/Pipit/Classes/Data/ResultsPage.php
index e6d7093..06ef1dc 100644
--- a/src/Pipit/Classes/Data/ResultsPage.php
+++ b/src/Pipit/Classes/Data/ResultsPage.php
@@ -116,7 +116,7 @@ public static function getNewResultsPage(int $page, int $resultsPerPage) {
         return $resultsPage;
     }
 
-    public function jsonSerialize() {
+    public function jsonSerialize():mixed {
         return get_object_vars($this);
     }
 }