diff --git a/phpstan.neon b/phpstan.neon
index cc591b292..283b543d8 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -15,5 +15,8 @@ parameters:
         # Caused by Symfony Validator (perhaps wrongly) returning the interface.
         - '#Cannot cast Symfony\\Component\\Validator\\ConstraintViolationListInterface to string.#'
 
+    parallel:
+        maximumNumberOfProcesses: 1
+
 includes:
     - vendor/phpstan/phpstan-doctrine/extension.neon