diff --git a/includes/common.inc b/includes/common.inc
index 31923f2..60f49b3 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -6481,6 +6481,66 @@ function element_set_attributes(array &$element, array $map) {
 }
 
 /**
+ * Computes the difference between arrays.
+ *
+ * This is just a wrapper around array_diff_assoc(). The only reason Drupal
+ * provides this function is in since PHP 5.4 casting of arrays to strings
+ * throws a notice. If you want to use array_diff_assoc() as it was up to PHP
+ * 5.3, then use this function but consider the consequences -- it should be
+ * rare to use this function.
+ *
+ * @param array $array1
+ *   The array to compare from.
+ * @param array $array2
+ *   The array to compare to.
+ *
+ * @return array
+ *   Returns an array containing all the values from array1 that are not present
+ *   in array2.
+ */
+function drupal_array_diff_assoc($array1, $array2) {
+  return @array_diff_assoc($array1, $array2);
+}
+
+/**
+ * Recursively computes the difference of arrays with additional index check.
+ *
+ * This is a version of array_diff_assoc() that supports multidimensional
+ * arrays.
+ *
+ * @param array $array1
+ *   The array to compare from.
+ * @param array $array2
+ *   The array to compare to.
+ *
+ * @return array
+ *   Returns an array containing all the values from array1 that are not present
+ *   in array2.
+ */
+function array_diff_assoc_recursive($array1, $array2) {
+  $difference = array();
+
+  foreach ($array1 as $key => $value) {
+    if (is_array($value)) {
+      if (!array_key_exists($key, $array2) || !is_array($array2[$key])) {
+        $difference[$key] = $value;
+      }
+      else {
+        $new_diff = array_diff_assoc_recursive($value, $array2[$key]);
+        if (!empty($new_diff)) {
+          $difference[$key] = $new_diff;
+        }
+      }
+    }
+    elseif (!array_key_exists($key, $array2) || $array2[$key] !== $value) {
+      $difference[$key] = $value;
+    }
+  }
+
+  return $difference;
+}
+
+/**
  * Sets a value in a nested array with variable depth.
  *
  * This helper function should be used when the depth of the array element you
diff --git a/modules/simpletest/tests/common.test b/modules/simpletest/tests/common.test
index 82e3055..e36a3f4 100644
--- a/modules/simpletest/tests/common.test
+++ b/modules/simpletest/tests/common.test
@@ -2630,3 +2630,87 @@ class FeedIconTest extends DrupalWebTestCase {
   }
 
 }
+
+/**
+ * Test array diff functions.
+ */
+class ArrayDiffUnitTest extends DrupalUnitTestCase {
+
+  /**
+   * Array to use for testing.
+   *
+   * @var array
+   */
+  protected $array1;
+
+  /**
+   * Array to use for testing.
+   *
+   * @var array
+   */
+  protected $array2;
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Array differences',
+      'description' => 'Performs tests on drupal_array_diff_assoc() and array_diff_assoc_recursive().',
+      'group' => 'System',
+    );
+  }
+
+  function setUp() {
+    parent::setUp();
+
+    $this->array1 = array(
+      'same' => 'yes',
+      'different' => 'no',
+      'array_empty_diff' => array(),
+      'null' => NULL,
+      'int_diff' => 1,
+      'array_diff' => array('same' => 'same', 'array' => array('same' => 'same')),
+      'array_compared_to_string' => array('value'),
+      'string_compared_to_array' => 'value',
+      'new' => 'new',
+    );
+    $this->array2 = array(
+      'same' => 'yes',
+      'different' => 'yes',
+      'array_empty_diff' => array(),
+      'null' => NULL,
+      'int_diff' => '1',
+      'array_diff' => array('same' => 'different', 'array' => array('same' => 'same')),
+      'array_compared_to_string' => 'value',
+      'string_compared_to_array' => array('value'),
+    );
+  }
+
+  /**
+   * Tests drupal_array_diff_assoc().
+   */
+  public function testArrayDiffAssoc() {
+    $expected = array(
+      'different' => 'no',
+      'new' => 'new',
+    );
+
+    $this->assertIdentical(drupal_array_diff_assoc($this->array1, $this->array2), $expected);
+  }
+
+
+  /**
+   * Tests array_diff_assoc_recursive().
+   */
+  public function testArrayDiffAssocRecursive() {
+    $expected = array(
+      'different' => 'no',
+      'int_diff' => 1,
+      // The 'array' key should not be returned, as it's the same.
+      'array_diff' => array('same' => 'same'),
+      'array_compared_to_string' => array('value'),
+      'string_compared_to_array' => 'value',
+      'new' => 'new',
+    );
+
+    $this->assertIdentical(array_diff_assoc_recursive($this->array1, $this->array2), $expected);
+  }
+}