diff --git a/packages/Config/RectorConfig.php b/packages/Config/RectorConfig.php
index 914b2c0eb40..b884b03ef30 100644
--- a/packages/Config/RectorConfig.php
+++ b/packages/Config/RectorConfig.php
@@ -6,6 +6,7 @@
 
 use Rector\Core\Configuration\Option;
 use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
+use Webmozart\Assert\Assert;
 
 /**
  * @api
@@ -19,6 +20,8 @@ final class RectorConfig extends ContainerConfigurator
      */
     public function paths(array $paths): void
     {
+        Assert::allString($paths);
+
         $parameters = $this->parameters();
         $parameters->set(Option::PATHS, $paths);
     }