diff --git a/lib/internal/v8_prof_polyfill.js b/lib/internal/v8_prof_polyfill.js
index 7d8d3ff0202d20..33e57835666650 100644
--- a/lib/internal/v8_prof_polyfill.js
+++ b/lib/internal/v8_prof_polyfill.js
@@ -77,7 +77,7 @@ try {
 const fd = fs.openSync(logFile, 'r');
 const buf = Buffer.allocUnsafe(4096);
 const dec = new (require('string_decoder').StringDecoder)('utf-8');
-var line = '';
+let line = '';
 
 {
   const message = versionCheck(peekline(), process.versions.v8);
@@ -125,7 +125,7 @@ function versionCheck(firstLine, expected) {
     return 'Unable to read v8-version from log file.';
   }
   // Compare major, minor and build; ignore the patch and candidate fields.
-  for (var i = 0; i < 3; i++)
+  for (let i = 0; i < 3; i++)
     if (curVer[i] !== firstLine[i + 1])
       return 'Testing v8 version different from logging version';
 }