diff --git a/README.md b/README.md
index 2c2c8fe..66a5b47 100644
--- a/README.md
+++ b/README.md
@@ -49,9 +49,15 @@ A string value that is used to specify custom-sort-order.json file path.
 
 ```js
 grunt.initConfig({
-  csscomb: {
+  foo : {
+    files: {
+      'dest/resorted-foo.css': ['src/foo.css'],
+    },
+  },
+  bar : {
     files: {
       'dest/resorted-foo.css': ['src/foo.css'],
+      'dest/resorted-bar.css': ['src/bar.css'],
     },
   },
 })
@@ -76,7 +82,7 @@ grunt.initConfig({
 
 ## Release History
 
-+ v0.5.0: Add error handling.
++ v0.5.0: Enable multiple files.
 + v0.4.0: Move to csscomb's repository.
 + v0.3.0: Fix sort option bug.
 + v0.2.0: Fix bugs.
diff --git a/package.json b/package.json
index 78f1dde..344f5b9 100644
--- a/package.json
+++ b/package.json
@@ -28,6 +28,9 @@
   "scripts": {
     "test": "grunt test"
   },
+  "dependencies": {
+    "async": "~0.2.9"
+  },
   "devDependencies": {
     "grunt-contrib-jshint": "~0.6.0",
     "grunt-contrib-clean": "~0.4.0",
diff --git a/tasks/csscomb.js b/tasks/csscomb.js
index 8d3c8fa..51993f7 100644
--- a/tasks/csscomb.js
+++ b/tasks/csscomb.js
@@ -6,61 +6,62 @@
  * Licensed under the MIT license.
  */
 'use strict';
-module.exports = function(grunt) {
+module.exports = function (grunt) {
 
-  grunt.registerMultiTask('csscomb', 'Sorting CSS properties in specific order.', function() {
-    var fs = require('fs'),
+  grunt.registerMultiTask('csscomb', 'Sorting CSS properties in specific order.', function () {
+
+    var async = require('async'),
+        fs = require('fs'),
         path = require('path'),
-        exec = require('child_process').exec;
-    var command,
-        done = this.async(),
         realPath = path.dirname(fs.realpathSync(__filename)),
-        cssComb = 'php ' + realPath + '/lib/csscomb.php',
-        fileSrc = '',
-        fileDest = '',
-        fileSort = '',
-        options = this.options({
-          sortOrder: null
-        });
+        done = this.async();
 
-    if (options.sortOrder !== null) {
-      if (grunt.file.exists(options.sortOrder)) {
-        fileSort = ' -s ' + options.sortOrder;
-      } else {
-        grunt.log.error('Custom sort .json file not found.');
-        return false;
-      }
-    }
+    async.eachSeries(this.files, function (file, next) {
+      var args = [],
+          child = {
+            cmd: 'php',
+            args: args
+          },
+          options = grunt.task.current.options({
+            sortOrder: null
+          });
 
-    function puts(error, stdout, stderr) {
-      if (error !== null) {
-        grunt.log.error(error);
+      args.push(realPath + '/lib/csscomb.php');
 
-      } else {
-        grunt.log.ok(stdout);
+      if (options.sortOrder !== null) {
+        if (grunt.file.exists(options.sortOrder)) {
+          args.push('-s', options.sortOrder);
+        } else {
+          grunt.log.error('Custom sort .json file not found.');
+          return false;
+        }
       }
-    }
 
-    this.files.forEach(function(file) {
-      fileSrc = file.src.filter(function(filepath) {
+      var fileSrc = file.src.filter(function (filepath) {
         // Remove nonexistent files (it's up to you to filter or warn here).
         if (!grunt.file.exists(filepath)) {
           grunt.log.warn('Source file "' + filepath + '" not found.');
           return false;
         } else {
-          return true;
+          return filepath;
         }
-      }).map(function(filepath) {
-        return filepath;
       });
-      fileSrc = ' -i ' + fileSrc;
+      args.push('-i', fileSrc);
+
       if (file.dest !== null) {
-        fileDest = ' -o ' + file.dest;
+        args.push('-o', file.dest);
       }
-      command = cssComb + fileSort + fileSrc + fileDest;
-      exec(command, puts);
-      grunt.verbose.writeln('`' + command + '` was initiated.');
-    });
-                
+
+      grunt.util.spawn(child, function (error, result, code) {
+        if (error !== null) {
+          grunt.log.error(error);
+        } else {
+          grunt.log.ok(result);
+          next();
+        }
+      });
+      grunt.verbose.ok('`php ' + child.args.join(' ') + '` was initiated.');
+    }, done);
+
   });
 };
\ No newline at end of file
diff --git a/test/fixtures/multi1.css b/test/fixtures/multi1.css
index 3c53943..c3944af 100644
--- a/test/fixtures/multi1.css
+++ b/test/fixtures/multi1.css
@@ -1,13 +1,13 @@
 .multi1 {
-	text-align: center;
-	border-color: 1px #000 solid;
-	background-color: red;
-	height: 100px;
+	z-index: 100;
 	display: block;
-	font-weight: bold;
-	width: 100px;
+	visibility: hidden;
 	max-height: 44px;
+	width: 100px;
+	height: 100px;
+	border-color: 1px #000 solid;
+	background-color: red;
 	vertical-align: 5px;
-	visibility: hidden;
-	z-index: 100;
+	text-align: center;
+	font-weight: bold;
 }
\ No newline at end of file
diff --git a/test/fixtures/multi2.css b/test/fixtures/multi2.css
index 300aee4..2ec4d0b 100644
--- a/test/fixtures/multi2.css
+++ b/test/fixtures/multi2.css
@@ -1,13 +1,13 @@
 .multi2 {
-	width: 10px;
-	border: 1px #fff solid;
 	position: absolute;
-	z-index: 10;
-	margin: 10px;
-	left: 10px;
-	height: 10px;
-	float: left;
 	top: 10px;
+	left: 10px;
+	z-index: 10;
 	display: table;
+	float: left;
+	margin: 10px;
 	padding: 10px;
+	width: 10px;
+	height: 10px;
+	border: 1px #fff solid;
 }
\ No newline at end of file
diff --git a/test/fixtures/style.css b/test/fixtures/style.css
index 1b94f30..1ebc083 100644
--- a/test/fixtures/style.css
+++ b/test/fixtures/style.css
@@ -1,8 +1,8 @@
 .comb {
-	text-align: center;
 	width: 100px;
-	background-color: red;
 	height: 100px;
-	display: block;
+	background-color: red;
+	text-align: center;
 	font-weight: bold;
+	display: block;
 }
\ No newline at end of file