diff --git a/Classes/Controller/CacheWarmupController.php b/Classes/Controller/CacheWarmupController.php
index 4389133b..9f4edddc 100644
--- a/Classes/Controller/CacheWarmupController.php
+++ b/Classes/Controller/CacheWarmupController.php
@@ -74,7 +74,7 @@ public function __invoke(Message\ServerRequestInterface $request): Message\Respo
             $warmupRequest = $this->mapper->map(ValueObject\Request\WarmupRequest::class, $request->getQueryParams());
         } catch (Valinor\Mapper\MappingError $error) {
             $errors = Valinor\Mapper\Tree\Message\Messages::flattenFromNode($error->node());
-            $messages = array_map('strval', $errors->toArray());
+            $messages = array_map(strval(...), $errors->toArray());
 
             $this->logger->error(
                 'Error during mapping of query parameters to warmup request object.',
diff --git a/Classes/Controller/CacheWarmupLegacyController.php b/Classes/Controller/CacheWarmupLegacyController.php
index b336169a..256873ef 100644
--- a/Classes/Controller/CacheWarmupLegacyController.php
+++ b/Classes/Controller/CacheWarmupLegacyController.php
@@ -65,7 +65,7 @@ public function __invoke(Message\ServerRequestInterface $request): Message\Respo
             $warmupRequest = $this->mapper->map(ValueObject\Request\WarmupRequest::class, $request->getQueryParams());
         } catch (Valinor\Mapper\MappingError $error) {
             $errors = Valinor\Mapper\Tree\Message\Messages::flattenFromNode($error->node());
-            $messages = array_map('strval', $errors->toArray());
+            $messages = array_map(strval(...), $errors->toArray());
 
             $this->logger->error(
                 'Error during mapping of query parameters to warmup request object.',
diff --git a/Classes/Http/Message/Event/WarmupFinishedEvent.php b/Classes/Http/Message/Event/WarmupFinishedEvent.php
index ff1883e5..f757aad4 100644
--- a/Classes/Http/Message/Event/WarmupFinishedEvent.php
+++ b/Classes/Http/Message/Event/WarmupFinishedEvent.php
@@ -85,12 +85,12 @@ public function getData(): array
                 'total' => \count($failedUrls) + \count($successfulUrls),
             ],
             'urls' => [
-                'failed' => array_map('strval', $failedUrls),
-                'successful' => array_map('strval', $successfulUrls),
+                'failed' => array_map(strval(...), $failedUrls),
+                'successful' => array_map(strval(...), $successfulUrls),
             ],
             'excluded' => [
-                'sitemaps' => array_map('strval', $this->result->getExcludedSitemaps()),
-                'urls' => array_map('strval', $this->result->getExcludedUrls()),
+                'sitemaps' => array_map(strval(...), $this->result->getExcludedSitemaps()),
+                'urls' => array_map(strval(...), $this->result->getExcludedUrls()),
             ],
             'messages' => $this->buildMessages($state),
         ];