diff --git a/test/big-data.js b/test/big-data.js
index b70cc8e..0998521 100644
--- a/test/big-data.js
+++ b/test/big-data.js
@@ -2,13 +2,12 @@ const test = require('tape')
 const b64 = require('../')
 
 test('convert big data to base64', function (t) {
-  let b64str, arr, i, length
   const big = new Uint8Array(64 * 1024 * 1024)
-  for (i = 0, length = big.length; i < length; ++i) {
+  for (let i = 0, length = big.length; i < length; ++i) {
     big[i] = i % 256
   }
-  b64str = b64.fromByteArray(big)
-  arr = b64.toByteArray(b64str)
+  const b64str = b64.fromByteArray(big)
+  const arr = b64.toByteArray(b64str)
   t.ok(equal(arr, big))
   t.equal(b64.byteLength(b64str), arr.length)
   t.end()
diff --git a/test/convert.js b/test/convert.js
index 7e553c8..e129c29 100644
--- a/test/convert.js
+++ b/test/convert.js
@@ -17,12 +17,11 @@ test('convert to base64 and back', function (t) {
 
   for (let i = 0; i < checks.length; i++) {
     const check = checks[i]
-    var b64Str, arr, str
 
-    b64Str = b64.fromByteArray(map(check, function (char) { return char.charCodeAt(0) }))
+    const b64Str = b64.fromByteArray(map(check, function (char) { return char.charCodeAt(0) }))
 
-    arr = b64.toByteArray(b64Str)
-    str = map(arr, function (byte) { return String.fromCharCode(byte) }).join('')
+    const arr = b64.toByteArray(b64Str)
+    const str = map(arr, function (byte) { return String.fromCharCode(byte) }).join('')
 
     t.equal(check, str, 'Checked ' + check)
     t.equal(b64.byteLength(b64Str), arr.length, 'Checked length for ' + check)
diff --git a/test/url-safe.js b/test/url-safe.js
index 23fb1cb..92d2dfa 100644
--- a/test/url-safe.js
+++ b/test/url-safe.js
@@ -6,7 +6,7 @@ test('decode url-safe style base64 strings', function (t) {
 
   let str = '//++/++/++//'
   let actual = b64.toByteArray(str)
-  for (var i = 0; i < actual.length; i++) {
+  for (let i = 0; i < actual.length; i++) {
     t.equal(actual[i], expected[i])
   }
 
@@ -14,7 +14,7 @@ test('decode url-safe style base64 strings', function (t) {
 
   str = '__--_--_--__'
   actual = b64.toByteArray(str)
-  for (i = 0; i < actual.length; i++) {
+  for (let i = 0; i < actual.length; i++) {
     t.equal(actual[i], expected[i])
   }