diff --git a/misc/ajax.js b/misc/ajax.js
index 9a85ee5e0ad..b1688e0d464 100644
--- a/misc/ajax.js
+++ b/misc/ajax.js
@@ -395,6 +395,13 @@ Drupal.ajax.prototype.commands = {
     alert(response.text, response.title);
   },
 
+  /**
+   * Command to provide the jQuery css() function.
+   */
+  css: function (ajax, response, status) {
+    $(response.selector).css(response.argument);
+  },
+
   /**
    * Command to set the settings that will be used for other commands in this response.
    */
diff --git a/modules/simpletest/tests/ajax.test b/modules/simpletest/tests/ajax.test
index 580cd4addc3..13e566bbc18 100644
--- a/modules/simpletest/tests/ajax.test
+++ b/modules/simpletest/tests/ajax.test
@@ -112,7 +112,10 @@ class AJAXCommandsTestCase extends AJAXTestCase {
     $command = $commands[1];
     $this->assertTrue($command['command'] == 'changed' && $command['selector'] == '#changed_div' && $command['asterisk'] == '#changed_div_mark_this', "'changed' AJAX command (with asterisk) issued with correct selector");
 
-    // 'css' command will go here when it is implemented.
+    // Tests the 'css' command.
+    $commands = $this->drupalPostAJAX($form_path, $edit, 'css_command_example');
+    $command = $commands[1];
+    $this->assertTrue($command['command'] == 'css' && $command['selector'] == '#css_div' && $command['argument']['background-color'] == 'blue', "'css' AJAX command issued with correct selector");
 
     // Tests the 'data' command.
     $commands = $this->drupalPostAJAX($form_path, $edit, 'data_command_example');
diff --git a/modules/simpletest/tests/ajax_forms_test.module b/modules/simpletest/tests/ajax_forms_test.module
index a0dcfc0e0ea..176f0697d25 100644
--- a/modules/simpletest/tests/ajax_forms_test.module
+++ b/modules/simpletest/tests/ajax_forms_test.module
@@ -149,11 +149,9 @@ function ajax_forms_test_ajax_commands_form($form, &$form_state) {
   );
 
   // Shows the AJAX 'css' command.
-  // @todo Note that this won't work until http://drupal.org/node/623320 lands.
   $form['css_command_example'] = array(
-    '#title' => t("AJAX CSS: Choose the color you'd like the '#box' div to be."),
-    '#type' => 'select',
-    '#options' => array('green' => 'green', 'blue' => 'blue'),
+    '#value' => t("Set the the '#box' div to be blue."),
+    '#type' => 'submit',
     '#ajax' => array(
       'callback' => 'ajax_forms_test_advanced_commands_css_callback',
     ),
@@ -289,7 +287,7 @@ function ajax_forms_test_advanced_commands_changed_asterisk_callback($form, $for
  */
 function ajax_forms_test_advanced_commands_css_callback($form, $form_state) {
   $selector = '#css_div';
-  $color = $form_state['values']['css_command_example'];
+  $color = 'blue';
 
   $commands = array();
   $commands[] = ajax_command_css($selector, array('background-color' => $color));