diff --git a/tests/phpunit.xml b/tests/phpunit.xml
index a4f95721..731c4bde 100644
--- a/tests/phpunit.xml
+++ b/tests/phpunit.xml
@@ -5,6 +5,7 @@
          cacheDirectory=".phpunit.cache"
          xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd"
          displayDetailsOnTestsThatTriggerWarnings="true"
+         processIsolation="true">
 >
   <testsuites>
     <testsuite name="Unit">