diff --git a/rules/DowngradePhp80/Rector/NullsafeMethodCall/DowngradeNullsafeToTernaryOperatorRector.php b/rules/DowngradePhp80/Rector/NullsafeMethodCall/DowngradeNullsafeToTernaryOperatorRector.php
index b3cb7e90..39362d51 100644
--- a/rules/DowngradePhp80/Rector/NullsafeMethodCall/DowngradeNullsafeToTernaryOperatorRector.php
+++ b/rules/DowngradePhp80/Rector/NullsafeMethodCall/DowngradeNullsafeToTernaryOperatorRector.php
@@ -54,6 +54,9 @@ public function refactor(Node $node): ?Ternary
         static $currentFile = null;
 
         if ($currentFile !== $this->file->getFilePath()) {
+            // the counter need start from 0 when visit new file to avoid random increment
+            // across files
+            // due to run on parallel
             $this->counter = 0;
             $currentFile = $this->file->getFilePath();
         }