diff --git a/lib/internal/process/main_thread_only.js b/lib/internal/process/main_thread_only.js
index 0cb3edbf9ad7b4..a610395be99cbf 100644
--- a/lib/internal/process/main_thread_only.js
+++ b/lib/internal/process/main_thread_only.js
@@ -77,7 +77,7 @@ 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