diff --git a/tests/vufind.php-cs-fixer.php b/tests/vufind.php-cs-fixer.php
index 903c19380e15..e0e125508af8 100644
--- a/tests/vufind.php-cs-fixer.php
+++ b/tests/vufind.php-cs-fixer.php
@@ -76,4 +76,5 @@
 return $config->setCacheFile($cacheDir . '/.code.cache')
     ->setRiskyAllowed(true)
     ->setRules($rules)
-    ->setFinder($finder);
+    ->setFinder($finder)
+    ->setParallelConfig(\PhpCsFixer\Runner\Parallel\ParallelConfigFactory::detect());
diff --git a/tests/vufind_templates.php-cs-fixer.php b/tests/vufind_templates.php-cs-fixer.php
index 84df993cb6ad..455710bc4b97 100644
--- a/tests/vufind_templates.php-cs-fixer.php
+++ b/tests/vufind_templates.php-cs-fixer.php
@@ -74,4 +74,5 @@
 return $config->setCacheFile($cacheDir . '/.template.cache')
     ->setRiskyAllowed(true)
     ->setRules($rules)
-    ->setFinder($finder);
+    ->setFinder($finder)
+    ->setParallelConfig(\PhpCsFixer\Runner\Parallel\ParallelConfigFactory::detect());