diff --git a/.php-cs-fixer.tests.php b/.php-cs-fixer.tests.php
index bf37256da58a..412400aebaee 100644
--- a/.php-cs-fixer.tests.php
+++ b/.php-cs-fixer.tests.php
@@ -31,7 +31,8 @@
     ->notName('#Foobar.php$#');
 
 $overrides = [
-    'void_return' => true,
+    'phpdoc_to_return_type' => true,
+    'void_return'           => true,
 ];
 
 return $config
diff --git a/tests/_support/Autoloader/FatalLocator.php b/tests/_support/Autoloader/FatalLocator.php
index 0b98fddc6eca..438c41480f01 100644
--- a/tests/_support/Autoloader/FatalLocator.php
+++ b/tests/_support/Autoloader/FatalLocator.php
@@ -34,7 +34,7 @@ class FatalLocator extends FileLocator
      *
      * @return false|string The path to the file, or false if not found.
      */
-    public function locateFile(string $file, ?string $folder = null, string $ext = 'php')
+    public function locateFile(string $file, ?string $folder = null, string $ext = 'php'): false|string
     {
         $folder ??= 'null';
 
diff --git a/tests/_support/Config/Services.php b/tests/_support/Config/Services.php
index 712c79004a0b..3cb7c53388c3 100644
--- a/tests/_support/Config/Services.php
+++ b/tests/_support/Config/Services.php
@@ -31,10 +31,8 @@ class Services extends BaseServices
      * The URI class provides a way to model and manipulate URIs.
      *
      * @param string|null $uri The URI string
-     *
-     * @return URI
      */
-    public static function uri(?string $uri = null, bool $getShared = true)
+    public static function uri(?string $uri = null, bool $getShared = true): URI
     {
         // Intercept our test case
         if ($uri === 'testCanReplaceFrameworkServices') {
diff --git a/tests/_support/Entity/Cast/CastPassParameters.php b/tests/_support/Entity/Cast/CastPassParameters.php
index 2cbfce0f324b..3f304e3622a0 100644
--- a/tests/_support/Entity/Cast/CastPassParameters.php
+++ b/tests/_support/Entity/Cast/CastPassParameters.php
@@ -22,10 +22,8 @@ class CastPassParameters extends BaseCast
      *
      * @param mixed $value  Data
      * @param array $params Additional param
-     *
-     * @return mixed
      */
-    public static function set($value, array $params = [])
+    public static function set($value, array $params = []): string
     {
         return $value . ':' . json_encode($params);
     }
diff --git a/tests/system/Files/FileTest.php b/tests/system/Files/FileTest.php
index b8e82edd02fd..c74c6b63ffeb 100644
--- a/tests/system/Files/FileTest.php
+++ b/tests/system/Files/FileTest.php
@@ -172,7 +172,7 @@ public function testGetDestination(): void
     /**
      * @return array<string, array<int, FileSizeUnit>>
      */
-    public static function provideGetSizeData()
+    public static function provideGetSizeData(): array
     {
         return [
             'returns KB binary' => [
diff --git a/tests/system/Models/TimestampModelTest.php b/tests/system/Models/TimestampModelTest.php
index ce2675a2d89d..9af7cd3b9547 100644
--- a/tests/system/Models/TimestampModelTest.php
+++ b/tests/system/Models/TimestampModelTest.php
@@ -40,7 +40,7 @@ protected function tearDown(): void
     /**
      * @return int|string Insert ID
      */
-    private function allowDatesPrepareOneRecord(array $data)
+    private function allowDatesPrepareOneRecord(array $data): int|string
     {
         $this->createModel(UserTimestampModel::class);
         $this->db->table('user')->truncate();
@@ -60,7 +60,7 @@ private function allowDatesPrepareOneRecord(array $data)
     /**
      * @return int|string Insert ID
      */
-    private function doNotAllowDatesPrepareOneRecord(array $data)
+    private function doNotAllowDatesPrepareOneRecord(array $data): int|string
     {
         $this->createModel(UserTimestampModel::class);
         $this->db->table('user')->truncate();
diff --git a/tests/system/Test/BootstrapFCPATHTest.php b/tests/system/Test/BootstrapFCPATHTest.php
index cc03ef99b1b7..2af9b87b560d 100644
--- a/tests/system/Test/BootstrapFCPATHTest.php
+++ b/tests/system/Test/BootstrapFCPATHTest.php
@@ -100,10 +100,7 @@ private function fileContents(): string
         return $fileContents . 'echo FCPATH;' . PHP_EOL;
     }
 
-    /**
-     * @return false|string
-     */
-    private function readOutput(string $file)
+    private function readOutput(string $file): false|string
     {
         ob_start();
         system('php -f ' . $file);