diff --git a/README.md b/README.md
index 1770a68..b55cf47 100644
--- a/README.md
+++ b/README.md
@@ -5,11 +5,11 @@ 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). 
+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:
 
 ```
@@ -29,11 +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/gruntjs/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:
 
@@ -54,18 +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 
- - *v0.3.0*: grunt-wkhtmltopdf is now a multi-task
- - *v0.4.0*: 
+ - *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 
+    - 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/tasks/wkhtmltopdf.js b/tasks/wkhtmltopdf.js
index 6f6dc05..375915d 100644
--- a/tasks/wkhtmltopdf.js
+++ b/tasks/wkhtmltopdf.js
@@ -18,7 +18,13 @@ module.exports = function(grunt) {
 
   grunt.registerMultiTask('wkhtmltopdf', 'Your task description goes here.', function() {
 
-    this.files.forEach(function(file) {
+    // 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;
+
+    // iterate through each file grouping
+    files.forEach(function(file, filesIndex) {
 
       var pathlib = require('path');
       // calculate the destination directory and ensure it exists, since
@@ -30,7 +36,7 @@ module.exports = function(grunt) {
       }
       grunt.file.mkdir(destPath);
 
-      file.src.forEach(function(src) {
+      file.src.forEach(function(src, srcIndex) {
 
         var dest = file.dest;
         // wkhtmltopdf seems to require that the destination be a file
@@ -51,19 +57,32 @@ module.exports = function(grunt) {
           "Converting " + src + " -> " + dest
         );
 
-        // Launch PhantomJS.
+        // 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: [
-              '--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
-              src,
-              dest
-            ],
+          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();
+            }
           }
         });
       });