diff --git a/.autod.conf.js b/.autod.conf.js
index 85abc36..a24dc86 100644
--- a/.autod.conf.js
+++ b/.autod.conf.js
@@ -7,6 +7,9 @@ module.exports = {
   exclude: [
     'test/fixtures',
   ],
+  dep: [
+    'long',
+  ],
   devdep: [
     'autod',
     'egg-bin',
diff --git a/.travis.yml b/.travis.yml
index ce21122..39d409a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,6 +3,7 @@ language: node_js
 node_js:
   - '8'
   - '10'
+  - '11'
 install:
   - npm i npminstall && npminstall
 script:
diff --git a/appveyor.yml b/appveyor.yml
index 981e82b..7cce29a 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -2,6 +2,7 @@ environment:
   matrix:
     - nodejs_version: '8'
     - nodejs_version: '10'
+    - nodejs_version: '11'
 
 install:
   - ps: Install-Product node $env:nodejs_version
diff --git a/benchmark/require.js b/benchmark/require.js
new file mode 100644
index 0000000..ee87372
--- /dev/null
+++ b/benchmark/require.js
@@ -0,0 +1,5 @@
+'use strict';
+
+console.time('byte');
+require('..');
+console.timeEnd('byte');
diff --git a/lib/byte.js b/lib/byte.js
index 936c83f..590744a 100644
--- a/lib/byte.js
+++ b/lib/byte.js
@@ -1,16 +1,28 @@
 'use strict';
 
-const Long = require('long');
-const debug = require('debug')('byte');
+const importLazy = require('import-lazy')(require);
+const Long = importLazy('long');
 const numbers = require('./number');
-const utility = require('utility');
 
+const MAX_SAFE_INTEGER_STR = '9007199254740991';
+const MAX_SAFE_INTEGER_STR_LENGTH = 16; // '9007199254740991'.length
 const DEFAULT_SIZE = 1024;
 const BIG_ENDIAN = 1;
 const LITTLE_ENDIAN = 2;
 const MAX_INT_31 = Math.pow(2, 31);
 const ONE_HUNDRED_MB = 100 * 1024 * 1024;
 
+function isSafeNumberString(s) {
+  if (s[0] === '-') {
+    s = s.substring(1);
+  }
+  if (s.length < MAX_SAFE_INTEGER_STR_LENGTH ||
+    (s.length === MAX_SAFE_INTEGER_STR_LENGTH && s <= MAX_SAFE_INTEGER_STR)) {
+    return true;
+  }
+  return false;
+}
+
 function ByteBuffer(options) {
   options = options || {};
   this._order = options.order || BIG_ENDIAN;
@@ -53,10 +65,8 @@ ByteBuffer.prototype._checkSize = function(afterSize) {
   if (this._size >= afterSize) {
     return;
   }
-  const old = this._size;
   this._size = afterSize * 2;
   this._limit = this._size;
-  debug('allocate new Buffer: from %d to %d bytes', old, this._size);
   const bytes = Buffer.alloc(this._size);
   this._bytes.copy(bytes, 0);
   this._bytes = bytes;
@@ -228,7 +238,7 @@ ByteBuffer.prototype.putLong = function(index, value) {
 
   let isNumber = typeof value === 'number';
   // convert safe number string to number
-  if (!isNumber && utility.isSafeNumberString(value)) {
+  if (!isNumber && isSafeNumberString(value)) {
     isNumber = true;
     value = Number(value);
   }
diff --git a/package.json b/package.json
index 684c156..e0827c1 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
   ],
   "scripts": {
     "autod": "autod",
-    "lint": "eslint lib test *.js",
+    "lint": "eslint lib test --ext .js",
     "test": "npm run lint && egg-bin test",
     "test-local": "egg-bin test",
     "cov": "egg-bin cov",
@@ -18,18 +18,17 @@
     "optimized": "node --allow-natives-syntax --trace_opt --trace_deopt test/optimized.js"
   },
   "dependencies": {
-    "debug": "^3.1.0",
-    "long": "^4.0.0",
-    "utility": "^1.13.1"
+    "import-lazy": "^3.1.0",
+    "long": "^4.0.0"
   },
   "devDependencies": {
-    "autod": "^3.0.1",
+    "autod": "^3.1.0",
     "beautify-benchmark": "^0.2.4",
     "benchmark": "^2.1.4",
-    "egg-bin": "^4.7.0",
-    "egg-ci": "^1.8.0",
-    "eslint": "^4.19.1",
-    "eslint-config-egg": "^7.0.0",
+    "egg-bin": "^4.12.2",
+    "egg-ci": "^1.11.0",
+    "eslint": "^5.16.0",
+    "eslint-config-egg": "^7.3.1",
     "fastbench": "^1.0.1",
     "optimized": "^1.2.0"
   },
@@ -54,7 +53,7 @@
     "node": ">= 8.0.0"
   },
   "ci": {
-    "version": "8, 10"
+    "version": "8, 10, 11"
   },
   "author": "fengmk2 <fengmk2@gmail.com> (http://fengmk2.com)",
   "license": "MIT"
diff --git a/test/byte.test.js b/test/byte.test.js
index ff7285a..c26a024 100644
--- a/test/byte.test.js
+++ b/test/byte.test.js
@@ -19,7 +19,7 @@ describe('byte.test.js', function() {
       bytes.putString('');
       bytes.putString('');
       bytes.putString(null);
-      bytes.putString(new Buffer(''));
+      bytes.putString(Buffer.from(''));
       bytes.putString(0, '');
 
       bytes.position(0);
@@ -35,10 +35,10 @@ describe('byte.test.js', function() {
       assert(bytes.getString(0) === 'foo, 中文');
       bytes.putString(0, 'foo, 中国');
       assert(bytes.getString(0) === 'foo, 中国');
-      bytes.putString(0, new Buffer('foo, 中国'));
+      bytes.putString(0, Buffer.from('foo, 中国'));
       assert(bytes.getString(0) === 'foo, 中国');
       bytes.putString('foo2');
-      assert(bytes.getString(new Buffer('foo, 中国').length + 4) === 'foo2');
+      assert(bytes.getString(Buffer.from('foo, 中国').length + 4) === 'foo2');
 
       bytes.position(0);
       assert(bytes.getString() === 'foo, 中国');
@@ -60,7 +60,7 @@ describe('byte.test.js', function() {
       bytes.putCString('bar123123, \u0000中文\u0000');
       bytes.putCString('foo2foo, \u0000中文\u0000');
       assert(
-        bytes.getCString(new Buffer('bar123123, \u0000中文\u0000').length + 4 + 1) === 'foo2foo, \u0000中文\u0000'
+        bytes.getCString(Buffer.from('bar123123, \u0000中文\u0000').length + 4 + 1) === 'foo2foo, \u0000中文\u0000'
       );
 
       bytes.position(0);
@@ -440,21 +440,21 @@ describe('byte.test.js', function() {
       assert(bytes.toString() === '<ByteBuffer 02 01>');
       assert(bytes.get(1) === 1);
 
-      bytes.put(new Buffer([ 255, 255, 255 ]));
+      bytes.put(Buffer.from([ 255, 255, 255 ]));
       assert(bytes.toString() === '<ByteBuffer 02 01 ff ff ff>');
-      assert.deepEqual(bytes.get(2, 3), new Buffer([ 255, 255, 255 ]));
+      assert.deepEqual(bytes.get(2, 3), Buffer.from([ 255, 255, 255 ]));
 
-      bytes.put(new Buffer([ 255, 254, 1 ]), 1, 2);
+      bytes.put(Buffer.from([ 255, 254, 1 ]), 1, 2);
       assert(bytes.toString() === '<ByteBuffer 02 01 ff ff ff fe 01>');
-      assert.deepEqual(bytes.get(5, 2), new Buffer([ 254, 1 ]));
+      assert.deepEqual(bytes.get(5, 2), Buffer.from([ 254, 1 ]));
 
       bytes.position(0);
-      assert.deepEqual(bytes.read(7), new Buffer([ 2, 1, 255, 255, 255, 254, 1 ]));
+      assert.deepEqual(bytes.read(7), Buffer.from([ 2, 1, 255, 255, 255, 254, 1 ]));
       assert(bytes.position() === 7);
 
       bytes.position(0);
       bytes.skip(5);
-      assert.deepEqual(bytes.read(2), new Buffer([ 254, 1 ]));
+      assert.deepEqual(bytes.read(2), Buffer.from([ 254, 1 ]));
       assert(bytes.position() === 7);
     });
   });
@@ -668,17 +668,17 @@ describe('byte.test.js', function() {
       const bytes = ByteBuffer.allocate(8);
       bytes.putInt(0);
       bytes.putInt(1);
-      assert.deepEqual(bytes.copy(4), new Buffer([ 0, 0, 0, 1 ]));
+      assert.deepEqual(bytes.copy(4), Buffer.from([ 0, 0, 0, 1 ]));
     });
 
     it('should copy(start, end)', function() {
       const bytes = ByteBuffer.allocate(9);
       bytes.putInt(0);
       bytes.putInt(1);
-      assert.deepEqual(bytes.copy(0, 8), new Buffer([ 0, 0, 0, 0, 0, 0, 0, 1 ]));
-      assert.deepEqual(bytes.copy(0, 9), new Buffer([ 0, 0, 0, 0, 0, 0, 0, 1 ]));
-      assert.deepEqual(bytes.copy(0, 4), new Buffer([ 0, 0, 0, 0 ]));
-      assert.deepEqual(bytes.copy(4, 8), new Buffer([ 0, 0, 0, 1 ]));
+      assert.deepEqual(bytes.copy(0, 8), Buffer.from([ 0, 0, 0, 0, 0, 0, 0, 1 ]));
+      assert.deepEqual(bytes.copy(0, 9), Buffer.from([ 0, 0, 0, 0, 0, 0, 0, 1 ]));
+      assert.deepEqual(bytes.copy(0, 4), Buffer.from([ 0, 0, 0, 0 ]));
+      assert.deepEqual(bytes.copy(4, 8), Buffer.from([ 0, 0, 0, 1 ]));
     });
   });
 
@@ -751,11 +751,11 @@ describe('byte.test.js', function() {
       const bytes = ByteBuffer.allocate(4);
       bytes.putInt(1);
       bytes.flip(); // switch to read mode
-      const buf = new Buffer(4);
+      const buf = Buffer.alloc(4);
       bytes.get(buf);
-      assert.deepEqual(buf, new Buffer([ 0, 0, 0, 1 ]));
+      assert.deepEqual(buf, Buffer.from([ 0, 0, 0, 1 ]));
 
-      const buf2 = new Buffer(1);
+      const buf2 = Buffer.alloc(1);
       assert.throws(function() {
         bytes.get(buf2);
       }, null, 'BufferOverflowException');
@@ -766,11 +766,11 @@ describe('byte.test.js', function() {
       bytes.putInt(1);
       bytes.putInt(5);
       bytes.flip(); // switch to read mode
-      const buf = new Buffer(4);
+      const buf = Buffer.alloc(4);
       bytes.get(buf);
-      assert.deepEqual(buf, new Buffer([ 0, 0, 0, 1 ]));
+      assert.deepEqual(buf, Buffer.from([ 0, 0, 0, 1 ]));
       bytes.get(buf);
-      assert.deepEqual(buf, new Buffer([ 0, 0, 0, 5 ]));
+      assert.deepEqual(buf, Buffer.from([ 0, 0, 0, 5 ]));
     });
   });
 
@@ -807,7 +807,7 @@ describe('byte.test.js', function() {
     it('should fill hello', function() {
       const str = 'hello';
       bytes.putRawString(str);
-      const buff = new Buffer(10);
+      const buff = Buffer.alloc(10);
       initBuff(buff);
       const copied = bytes.memcpy(buff);
 
@@ -820,7 +820,7 @@ describe('byte.test.js', function() {
     });
 
     it('should fill hel', function() {
-      const buff = new Buffer(3);
+      const buff = Buffer.alloc(3);
       initBuff(buff);
       const copied = bytes.memcpy(buff);