diff --git a/src/cjs/index.cjs b/src/cjs/index.cjs
index 07524c6..a05f0b2 100644
--- a/src/cjs/index.cjs
+++ b/src/cjs/index.cjs
@@ -7,10 +7,7 @@
 Object.defineProperty(exports, '__esModule', { value: true })
 function base (ALPHABET) {
   if (ALPHABET.length >= 255) { throw new TypeError('Alphabet too long') }
-  const BASE_MAP = new Uint8Array(256)
-  for (let j = 0; j < BASE_MAP.length; j++) {
-    BASE_MAP[j] = 255
-  }
+  const BASE_MAP = new Uint8Array(256).fill(255)
   for (let i = 0; i < ALPHABET.length; i++) {
     const x = ALPHABET.charAt(i)
     const xc = x.charCodeAt(0)
diff --git a/src/esm/index.js b/src/esm/index.js
index ce48a14..b79762b 100644
--- a/src/esm/index.js
+++ b/src/esm/index.js
@@ -5,10 +5,7 @@
 // file LICENSE or http://www.opensource.org/licenses/mit-license.php.
 function base (ALPHABET) {
   if (ALPHABET.length >= 255) { throw new TypeError('Alphabet too long') }
-  const BASE_MAP = new Uint8Array(256)
-  for (let j = 0; j < BASE_MAP.length; j++) {
-    BASE_MAP[j] = 255
-  }
+  const BASE_MAP = new Uint8Array(256).fill(255)
   for (let i = 0; i < ALPHABET.length; i++) {
     const x = ALPHABET.charAt(i)
     const xc = x.charCodeAt(0)
diff --git a/ts_src/index.ts b/ts_src/index.ts
index 5f2431a..fe29b79 100644
--- a/ts_src/index.ts
+++ b/ts_src/index.ts
@@ -7,10 +7,7 @@
 function base (ALPHABET: string): base.BaseConverter {
   if (ALPHABET.length >= 255) throw new TypeError('Alphabet too long')
 
-  const BASE_MAP = new Uint8Array(256)
-  for (let j = 0; j < BASE_MAP.length; j++) {
-    BASE_MAP[j] = 255
-  }
+  const BASE_MAP = new Uint8Array(256).fill(255)
 
   for (let i = 0; i < ALPHABET.length; i++) {
     const x = ALPHABET.charAt(i)