diff --git a/lib/internal/process/main_thread_only.js b/lib/internal/process/main_thread_only.js
index 8af402c57a6cb0..072498d5fe3101 100644
--- a/lib/internal/process/main_thread_only.js
+++ b/lib/internal/process/main_thread_only.js
@@ -76,7 +76,7 @@ function wrapPosixCredentialSetters(credentials) {
     if (!Array.isArray(groups)) {
       throw new ERR_INVALID_ARG_TYPE('groups', 'Array', groups);
     }
-    for (var i = 0; i < groups.length; i++) {
+    for (let i = 0; i < groups.length; i++) {
       validateId(groups[i], `groups[${i}]`);
     }
     // Result is 0 on success. A positive integer indicates that the