diff --git a/lib/v8.js b/lib/v8.js
index 5be59cb935c..32c2f3aa1b5 100644
--- a/lib/v8.js
+++ b/lib/v8.js
@@ -165,7 +165,7 @@ function getHeapSpaceStatistics() {
   const buffer = heapSpaceStatisticsBuffer;
   updateHeapSpaceStatisticsArrayBuffer();
 
-  for (var i = 0; i < kNumberOfHeapSpaces; i++) {
+  for (let i = 0; i < kNumberOfHeapSpaces; i++) {
     const propertyOffset = i * kHeapSpaceStatisticsPropertiesCount;
     heapSpaceStatistics[i] = {
       space_name: kHeapSpaces[i],