diff --git a/rules/DowngradePhp72/Rector/ClassMethod/DowngradeParameterTypeWideningRector.php b/rules/DowngradePhp72/Rector/ClassMethod/DowngradeParameterTypeWideningRector.php
index 53027791..b153bc67 100644
--- a/rules/DowngradePhp72/Rector/ClassMethod/DowngradeParameterTypeWideningRector.php
+++ b/rules/DowngradePhp72/Rector/ClassMethod/DowngradeParameterTypeWideningRector.php
@@ -141,6 +141,7 @@ public function configure(array $configuration): void
 
         foreach ($unsafeTypesToMethods as $key => $value) {
             Assert::string($key);
+            Assert::isArray($value);
             Assert::allString($value);
         }