diff --git a/grunt.js b/Gruntfile.js
similarity index 60%
rename from grunt.js
rename to Gruntfile.js
index 008da40..ccdf7bd 100644
--- a/grunt.js
+++ b/Gruntfile.js
@@ -1,12 +1,14 @@
+'use strict';
+
 module.exports = function(grunt) {
 
+  // Load grunt tasks automatically
+  require('load-grunt-tasks')(grunt);
+
   // Project configuration.
   grunt.initConfig({
-    test: {
-      files: ['test/**/*.js']
-    },
-    lint: {
-      files: ['grunt.js', 'tasks/**/*.js', 'test/**/*.js']
+    nodeunit: {
+      all: ['test/**/_test.js']
     },
     watch: {
       files: '<config:lint.files>',
@@ -25,16 +27,19 @@ module.exports = function(grunt) {
         boss: true,
         eqnull: true,
         node: true,
-        es5: true
       },
-      globals: {}
+      all: [
+        'Gruntfile.js',
+        'tasks/{,*/}*.js',
+        'test/{,*/}*.js',
+      ]
     }
   });
 
-  // Load local tasks.
-  grunt.loadTasks('tasks');
-
   // Default task.
-  grunt.registerTask('default', 'lint test');
+  grunt.registerTask('default', [
+    'jshint',
+    'nodeunit:all'
+  ]);
 
 };
diff --git a/README.md b/README.md
index 030dc8b..b55cf47 100644
--- a/README.md
+++ b/README.md
@@ -5,17 +5,20 @@ Convertion to PDF takes care of `@media print` CSS rules and preserves links to
 
 ## Getting Started
 
-### Setting up wkhtmltopdf 
+### Setting up wkhtmltopdf
 
 Download and install wkhtmltopdf from the [project page][wkhtmltopdf_dl].
 
-Make sure `wkhtmltopdf` is accessible from your `PATH` (Try `wkhtmltopdf -V` in your Terminal). 
-I'm on Mas OS X, so I created the following symlink to my `/usr/local/bin/` folder:
+Make sure `wkhtmltopdf` is accessible from your `PATH` (Try `wkhtmltopdf -V` in your Terminal).
+I'm on Mac OS X, so I created the following symlink to my `/usr/local/bin/` folder:
 
 ```
 ln -s /usr/local/bin/wkhtmltopdf.app/Contents/MacOS/wkhtmltopdf /usr/local/bin/wkhtmltopdf
 ```
 
+You can also install it via homebrew: `$ brew install wkhtmltopdf`.
+
+
 ### Use it with grunt
 
 Install this grunt plugin next to your project's [grunt.js gruntfile][getting_started] with: `npm install grunt-wkhtmltopdf`
@@ -26,11 +29,6 @@ Then add this line to your project's `grunt.js` gruntfile:
 grunt.loadNpmTasks('grunt-wkhtmltopdf');
 ```
 
-[wkhtmltopdf]: http://code.google.com/p/wkhtmltopdf/
-[wkhtmltopdf_dl]: http://code.google.com/p/wkhtmltopdf/downloads/list
-[grunt]: https://github.com/cowboy/grunt
-[getting_started]: https://github.com/cowboy/grunt/blob/master/docs/getting_started.md
-
 ## Documentation
 Simply add task definition in your gruntfile. See the folllowing example:
 
@@ -51,15 +49,61 @@ Simply add task definition in your gruntfile. See the folllowing example:
 
 Run `grunt wkhtmltopdf` to execute all the targets or `grunt wkhtmltopdf:targetname` to execute a specific target. Every `html` file defined by the `src` parameter will be turned into a PDF and saved to `dest` folder.
 
+### Sending arguments to `wkhtml2pdf`
+
+Arguments sent via the `args` key in the task definition will be forwarded to `wkhtml2pdf` as follow :
+
+```javascript
+    //...
+    wkhtmltopdf: {
+      prod: {
+        src: 'path/to/some/html/file/*.html',
+        dest: 'pdf/output/',
+        args: [
+          '--dpi', '96',
+          '--print-media-type',
+          '--grayscale'
+        ]
+      }
+    },
+    //...
+```
+
+Defining custom arguments will override default ones:
+
+```javascript
+// grunt-wkhtml2pdf default arguments
+var args = [
+  '--dpi', '96',
+  '--print-media-type'
+]
+```
+
+See [wkhtml2pdf documentation][wkhtmltopdf_doc] for available options
+
 ## Contributing
 In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using [grunt][grunt].
 
 ## Release History
 
- - *v0.1.0*: First Release
- - *v0.2.0*: Fixed compatibility with grunt 0.4 
+ - *v0.5.0*:
+    - Merged [#12](https://github.com/dharFr/grunt-wkhtmltopdf/pull/12) (Fix [#11](https://github.com/dharFr/grunt-wkhtmltopdf/issues/11)) : Added async support
+    - Merged [#9](https://github.com/dharFr/grunt-wkhtmltopdf/pull/9) : Added ability to override the arguments
+ - *v0.4.0*:
+    - Update project config files to work with Grunt 0.4
+    - Update wkthmltopdf task to use Grunt 0.4 multi-task API
+    - Improve predictability of the destination for created PDFs
  - *v0.3.0*: grunt-wkhtmltopdf is now a multi-task
+ - *v0.2.0*: Fixed compatibility with grunt 0.4
+ - *v0.1.0*: First Release
 
 ## License
-Copyright (c) 2012 Olivier Audard  
+Copyright (c) 2012 Olivier Audard
 Licensed under the MIT license.
+
+
+[wkhtmltopdf]: http://wkhtmltopdf.org/
+[wkhtmltopdf_dl]: http://wkhtmltopdf.org/downloads.html
+[wkhtmltopdf_doc]: http://wkhtmltopdf.org/docs.html
+[grunt]: https://github.com/gruntjs/grunt
+[getting_started]: https://github.com/cowboy/grunt/blob/master/docs/getting_started.md
diff --git a/package.json b/package.json
index a677a37..4b0888f 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "grunt-wkhtmltopdf",
   "description": "Grunt Task that uses wkhtmltopdf to convert HTML files to PDF",
-  "version": "0.3.0",
+  "version": "0.4.0",
   "homepage": "http://www.dhar.fr/grunt-wkhtmltopdf/",
   "author": {
     "name": "Olivier Audard",
@@ -30,10 +30,13 @@
     "test": "grunt test"
   },
   "dependencies": {
-    "grunt": "~0.3.9"
+    "grunt": "~0.4.1"
   },
   "devDependencies": {
-    "grunt": "~0.3.9"
+    "grunt": "~0.4.1",
+    "grunt-contrib-jshint": "^0.10.0",
+    "grunt-contrib-nodeunit": "^0.4.0",
+    "load-grunt-tasks": "^0.4.0"
   },
   "keywords": [
     "gruntplugin",
@@ -41,4 +44,4 @@
     "convert",
     "html"
   ]
-}
\ No newline at end of file
+}
diff --git a/tasks/wkhtmltopdf.js b/tasks/wkhtmltopdf.js
index ee673be..375915d 100644
--- a/tasks/wkhtmltopdf.js
+++ b/tasks/wkhtmltopdf.js
@@ -18,33 +18,73 @@ module.exports = function(grunt) {
 
   grunt.registerMultiTask('wkhtmltopdf', 'Your task description goes here.', function() {
 
-    var htmlFiles = grunt.file.expandFiles(this.file.src),
-        dest = (this.file.dest && this.file.dest !== '') ? this.file.dest + '/' : '';
+    // using grunt async support so we can be sure task doesn't
+    // end before PDF processing does: http://gruntjs.com/api/inside-tasks
+    var done = this.async(),
+        files = this.files;
 
-    grunt.log.writeln("pdf output is: " + dest);
+    // iterate through each file grouping
+    files.forEach(function(file, filesIndex) {
 
-    htmlFiles.forEach(function(srcpath) {
-      var dir = dest + srcpath.replace(/.*\/([^\/]+)\/[^\/]+\.html/, '$1');
+      var pathlib = require('path');
+      // calculate the destination directory and ensure it exists, since
+      // wkhtmltopdf won't create the PDF if the destination directory doesn't
+      // exist
+      var destPath = file.dest;
+      if (grunt.file.isFile(file.dest)) {
+        destPath = pathlib.dirname(file.dest);
+      }
+      grunt.file.mkdir(destPath);
 
-      // Create dest folder as wkhtmltopdf won't generate output if it doesn't exist
-      grunt.file.mkdir(dir);
-      var destpath  = dir + '/' +
-          srcpath.replace(/.*\/([^\/]+)\.html/, '$1.pdf');
+      file.src.forEach(function(src, srcIndex) {
 
-      // Launch PhantomJS.
-      helper.convert({
-        code: 90,
-        args: [
-            '--dpi', '96',        // workarround to wkhtmltopdf letter-spacing bug (see http://code.google.com/p/wkhtmltopdf/issues/detail?id=72)
-            '--print-media-type', // Use @print media type
-            srcpath,
-            destpath
-          ],
-        done: function(err) {
-          if (err) {
-            grunt.log('>>>', err);
-          }
+        var dest = file.dest;
+        // wkhtmltopdf seems to require that the destination be a file
+        // location, not a directory, so if the given destination is a
+        // directory then append the name of the source file but with the
+        // extension changed to .pdf
+        if (grunt.file.isDir(dest)) {
+          var srcFileName = pathlib.basename(src);
+          var srcFileExtension = pathlib.extname(src);
+          var destFileName = srcFileName.replace(
+            new RegExp(srcFileExtension + "$"), // match only the end of the string
+            ".pdf"
+          );
+          dest = pathlib.join(destPath + destFileName);
         }
+
+        grunt.log.writeln(
+          "Converting " + src + " -> " + dest
+        );
+
+        // default args
+        var args = [
+          '--dpi', '96',        // workarround to wkhtmltopdf letter-spacing bug (see http://code.google.com/p/wkhtmltopdf/issues/detail?id=72)
+          '--print-media-type'  // Use @print media type
+        ];
+
+        // overrides the args
+        if (file.args) {
+          args = file.args;
+        }
+
+        // adds the src and dest
+        args = args.concat([src, dest]);
+
+        // Launch wkhtmltopdf.
+        helper.convert({
+          code: 90,
+          args: args,
+          done: function(err) {
+            if (err) {
+              grunt.log('>>>', err);
+            }
+            // if this is the last src of the last file, we are done.
+            if((filesIndex+1 >= files.length) && (srcIndex+1 >= file.src.length)) {
+              done();
+            }
+          }
+        });
       });
     });
   });