diff --git a/.gitignore b/.gitignore
index 9880aa2..a31e983 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,5 @@ npm-debug.log
 .DS_Store
 .nyc_output/
 coverage/
+package-lock.json
+yarn.lock
diff --git a/.npmignore b/.npmignore
index 9134b5b..b5e3844 100644
--- a/.npmignore
+++ b/.npmignore
@@ -22,3 +22,4 @@ npm-debug.log*
 pids
 test
 test.js
+yarn.lock
diff --git a/index.js b/index.js
index f8ff71b..7bcbb32 100644
--- a/index.js
+++ b/index.js
@@ -56,7 +56,7 @@ module.exports = withConfigLoader(function (loadConfig) {
       var map
       var warnings = result.warnings().join('\n')
 
-      file.contents = new Buffer(result.css)
+      file.contents = Buffer.from(result.css)
 
       // Apply source map to the chain
       if (file.sourceMap) {
diff --git a/package.json b/package.json
index 5e9e3cd..d69bcfd 100644
--- a/package.json
+++ b/package.json
@@ -16,6 +16,9 @@
   "version": "8.0.0",
   "description": "PostCSS gulp plugin",
   "main": "index.js",
+  "engines": {
+    "node": ">=6"
+  },
   "scripts": {
     "coveralls": "coveralls < coverage/lcov.info",
     "pretest": "eslint *.js",
diff --git a/test.js b/test.js
index 2c6fe72..bca1c62 100644
--- a/test.js
+++ b/test.js
@@ -41,7 +41,7 @@ it('should transform css with multiple processors', function (cb) {
   })
 
   stream.write(new Vinyl({
-    contents: new Buffer('a { color: black }')
+    contents: Buffer.from('a { color: black }')
   }))
 
   stream.end()
@@ -64,7 +64,7 @@ it('should not transform css with out any processor', function (cb) {
   })
 
   stream.write(new Vinyl({
-    contents: new Buffer(css)
+    contents: Buffer.from(css)
   }))
 
   stream.end()
@@ -89,7 +89,7 @@ it('should correctly wrap postcss errors', function (cb) {
   })
 
   stream.write(new Vinyl({
-    contents: new Buffer('a {'),
+    contents: Buffer.from('a {'),
     path: path.resolve('testpath')
   }))
 
@@ -143,7 +143,7 @@ it('should generate source maps', function (cb) {
   init.write(new Vinyl({
     base: __dirname,
     path: __dirname + '/fixture.css',
-    contents: new Buffer('a { color: black }')
+    contents: Buffer.from('a { color: black }')
   }))
 
   init.end()
@@ -169,7 +169,7 @@ it('should correctly generate relative source map', function (cb) {
   init.write(new Vinyl({
     base: __dirname + '/src',
     path: __dirname + '/src/fixture.css',
-    contents: new Buffer('a { color: black }')
+    contents: Buffer.from('a { color: black }')
   }))
 
   init.end()
@@ -179,7 +179,7 @@ it('should correctly generate relative source map', function (cb) {
 
 describe('PostCSS Guidelines', function () {
 
-  var sandbox = sinon.sandbox.create()
+  var sandbox = sinon.createSandbox()
   var CssSyntaxError = function (message, source) {
     this.name = 'CssSyntaxError'
     this.message = message
@@ -241,7 +241,7 @@ describe('PostCSS Guidelines', function () {
     })
 
     stream.write(new Vinyl({
-      contents: new Buffer('a {}'),
+      contents: Buffer.from('a {}'),
       path: cssPath
     }))
 
@@ -265,7 +265,7 @@ describe('PostCSS Guidelines', function () {
     })
 
     stream.write(new Vinyl({
-      contents: new Buffer('a {}')
+      contents: Buffer.from('a {}')
     }))
 
     stream.end()
@@ -276,7 +276,7 @@ describe('PostCSS Guidelines', function () {
 
     var cssPath = __dirname + '/fixture.css'
     var file = new Vinyl({
-      contents: new Buffer('a {}'),
+      contents: Buffer.from('a {}'),
       path: cssPath
     })
     var plugins = [ doubler ]
@@ -308,7 +308,7 @@ describe('PostCSS Guidelines', function () {
 
     var cssPath = __dirname + '/fixture.css'
     var file = new Vinyl({
-      contents: new Buffer('a {}'),
+      contents: Buffer.from('a {}'),
       path: cssPath
     })
     var stream = postcss({ to: 'initial' })
@@ -355,7 +355,7 @@ describe('PostCSS Guidelines', function () {
       cb()
     })
     stream.end(new Vinyl({
-      contents: new Buffer('a {}'),
+      contents: Buffer.from('a {}'),
       path: cssPath
     }))
   })
@@ -375,7 +375,7 @@ describe('PostCSS Guidelines', function () {
       cb()
     })
     stream.end(new Vinyl({
-      contents: new Buffer('a {}'),
+      contents: Buffer.from('a {}'),
       path: cssPath
     }))
   })
@@ -395,7 +395,7 @@ describe('PostCSS Guidelines', function () {
       cb()
     })
     stream.end(new Vinyl({
-      contents: new Buffer('a {}'),
+      contents: Buffer.from('a {}'),
       path: cssPath,
       base: __dirname
     }))
@@ -432,7 +432,7 @@ describe('PostCSS Guidelines', function () {
     })
 
     var file = new Vinyl({
-      contents: new Buffer('a {}'),
+      contents: Buffer.from('a {}'),
       path: cssPath
     })
     file.sourceMap = {}
@@ -453,7 +453,7 @@ describe('PostCSS Guidelines', function () {
     })
 
     stream.write(new Vinyl({
-      contents: new Buffer('a {}')
+      contents: Buffer.from('a {}')
     }))
 
     stream.end()
@@ -485,7 +485,7 @@ describe('PostCSS Guidelines', function () {
     })
 
     stream.write(new Vinyl({
-      contents: new Buffer('a {}'),
+      contents: Buffer.from('a {}'),
       path: cssPath
     }))
 
@@ -520,7 +520,7 @@ describe('PostCSS Guidelines', function () {
     })
 
     stream.write(new Vinyl({
-      contents: new Buffer('a {}'),
+      contents: Buffer.from('a {}'),
       path: cssPath
     }))