diff --git a/tests/ExampleTest.php b/tests/ExampleTest.php
index c46b476..d9d0626 100644
--- a/tests/ExampleTest.php
+++ b/tests/ExampleTest.php
@@ -46,7 +46,7 @@
     $client->predict([], fnIndex: 6, raw: true);
     $client->predict(['hi'], fnIndex: 2, raw: true);
     $client->predict([null, null], fnIndex: 3, raw: true);
-    $response = $client->predict([null, null, "", 0.9, 256, 0.6, 1.2], fnIndex: 4);
+    $response = $client->predict([null, null, '', 0.9, 256, 0.6, 1.2], fnIndex: 4);
 
     $value = $response->getOutput();