diff --git a/src/Api/Helpers/Json.php b/src/Api/Helpers/Json.php
index e90c0d4..e4dc953 100644
--- a/src/Api/Helpers/Json.php
+++ b/src/Api/Helpers/Json.php
@@ -55,7 +55,7 @@ class Json
     public static function sendError($message = 'Bad Request', int $status = 400, ?LoggerInterface $logger = null): void
     {
         $payload = [
-            'error' => is_array($message) ? $message : ['message' => $message]
+            'error' => \is_array($message) ? $message : ['message' => $message]
         ];
 
         if ($logger) {
diff --git a/src/ElixForms/Auth/ElixFormsApiClient.php b/src/ElixForms/Auth/ElixFormsApiClient.php
index b8edb53..34c47ec 100644
--- a/src/ElixForms/Auth/ElixFormsApiClient.php
+++ b/src/ElixForms/Auth/ElixFormsApiClient.php
@@ -40,7 +40,7 @@ class ElixFormsApiClient
         $payload = $this->getJson($url, $authToken, $username, 'LookupByStatus');
         $requests = $payload['value']['requests'] ?? [];
 
-        if (!is_array($requests)) {
+        if (!\is_array($requests)) {
             throw new ElixFormsException('Risposta LookupByStatus non valida: requests deve essere un array.');
         }
 
@@ -74,7 +74,7 @@ class ElixFormsApiClient
         $payload = $this->getJson($url, $authToken, $username, 'GetExportTags');
         $exportTags = $payload['value']['exportTags'] ?? [];
 
-        if (!is_array($exportTags)) {
+        if (!\is_array($exportTags)) {
             throw new ElixFormsException('Risposta GetExportTags non valida: exportTags deve essere un array.');
         }
 
@@ -105,12 +105,12 @@ class ElixFormsApiClient
 
         $payload = $response['json'] ?? null;
         $jsonError = JSON_ERROR_NONE;
-        if (!is_array($payload) && isset($response['body']) && is_string($response['body'])) {
+        if (!\is_array($payload) && isset($response['body']) && \is_string($response['body'])) {
             $payload = json_decode($response['body'], true);
             $jsonError = json_last_error();
         }
 
-        if (!is_array($payload) || $jsonError !== JSON_ERROR_NONE) {
+        if (!\is_array($payload) || $jsonError !== JSON_ERROR_NONE) {
             throw new ElixFormsException(\sprintf(
                 'Risposta non valida da %s: atteso JSON.',
                 $operation