diff --git a/composer.json b/composer.json
index bc5ad81b..ce4f0d0c 100644
--- a/composer.json
+++ b/composer.json
@@ -8,7 +8,7 @@
     "keywords": ["assert", "assertion", "validation"],
     "require": {
         "php": ">=5.3",
-        "ext-mbstring": "*"
+        "ext-intl": "*"
     },
     "require-dev": {
         "phpunit/phpunit": "@stable"
diff --git a/lib/Assert/Assertion.php b/lib/Assert/Assertion.php
index 8d2a554f..133f3b2f 100644
--- a/lib/Assert/Assertion.php
+++ b/lib/Assert/Assertion.php
@@ -36,13 +36,13 @@
  * @method static void nullOrNotNull($value, $message = null, $propertyPath = null)
  * @method static void nullOrString($value, $message = null, $propertyPath = null)
  * @method static void nullOrRegex($value, $pattern, $message = null, $propertyPath = null)
- * @method static void nullOrLength($value, $length, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void nullOrMinLength($value, $minLength, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void nullOrMaxLength($value, $maxLength, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void nullOrBetweenLength($value, $minLength, $maxLength, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void nullOrStartsWith($string, $needle, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void nullOrEndsWith($string, $needle, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void nullOrContains($string, $needle, $message = null, $propertyPath = null, $encoding = "utf8")
+ * @method static void nullOrLength($value, $length, $message = null, $propertyPath = null)
+ * @method static void nullOrMinLength($value, $minLength, $message = null, $propertyPath = null)
+ * @method static void nullOrMaxLength($value, $maxLength, $message = null, $propertyPath = null)
+ * @method static void nullOrBetweenLength($value, $minLength, $maxLength, $message = null, $propertyPath = null)
+ * @method static void nullOrStartsWith($string, $needle, $message = null, $propertyPath = null)
+ * @method static void nullOrEndsWith($string, $needle, $message = null, $propertyPath = null)
+ * @method static void nullOrContains($string, $needle, $message = null, $propertyPath = null)
  * @method static void nullOrChoice($value, $choices, $message = null, $propertyPath = null)
  * @method static void nullOrInArray($value, $choices, $message = null, $propertyPath = null)
  * @method static void nullOrNumeric($value, $message = null, $propertyPath = null)
@@ -76,7 +76,6 @@
  * @method static void nullOrChoicesNotEmpty($values, $choices, $message = null, $propertyPath = null)
  * @method static void nullOrMethodExists($value, $object, $message = null, $propertyPath = null)
  * @method static void nullOrIsObject($value, $message = null, $propertyPath = null)
- * @method static void nullOrDate($value, $format, $message = null, $propertyPath = null)
  * @method static void allEq($value, $value2, $message = null, $propertyPath = null)
  * @method static void allSame($value, $value2, $message = null, $propertyPath = null)
  * @method static void allNotEq($value1, $value2, $message = null, $propertyPath = null)
@@ -92,13 +91,13 @@
  * @method static void allNotNull($value, $message = null, $propertyPath = null)
  * @method static void allString($value, $message = null, $propertyPath = null)
  * @method static void allRegex($value, $pattern, $message = null, $propertyPath = null)
- * @method static void allLength($value, $length, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void allMinLength($value, $minLength, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void allMaxLength($value, $maxLength, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void allBetweenLength($value, $minLength, $maxLength, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void allStartsWith($string, $needle, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void allEndsWith($string, $needle, $message = null, $propertyPath = null, $encoding = "utf8")
- * @method static void allContains($string, $needle, $message = null, $propertyPath = null, $encoding = "utf8")
+ * @method static void allLength($value, $length, $message = null, $propertyPath = null)
+ * @method static void allMinLength($value, $minLength, $message = null, $propertyPath = null)
+ * @method static void allMaxLength($value, $maxLength, $message = null, $propertyPath = null)
+ * @method static void allBetweenLength($value, $minLength, $maxLength, $message = null, $propertyPath = null)
+ * @method static void allStartsWith($string, $needle, $message = null, $propertyPath = null)
+ * @method static void allEndsWith($string, $needle, $message = null, $propertyPath = null)
+ * @method static void allContains($string, $needle, $message = null, $propertyPath = null)
  * @method static void allChoice($value, $choices, $message = null, $propertyPath = null)
  * @method static void allInArray($value, $choices, $message = null, $propertyPath = null)
  * @method static void allNumeric($value, $message = null, $propertyPath = null)
@@ -132,7 +131,6 @@
  * @method static void allChoicesNotEmpty($values, $choices, $message = null, $propertyPath = null)
  * @method static void allMethodExists($value, $object, $message = null, $propertyPath = null)
  * @method static void allIsObject($value, $message = null, $propertyPath = null)
- * @method static void allDate($value, $format, $message = null, $propertyPath = null)
  * METHODEND
  */
 class Assertion
@@ -192,7 +190,6 @@ class Assertion
     const INVALID_LESS_OR_EQUAL     = 211;
     const INVALID_GREATER           = 212;
     const INVALID_GREATER_OR_EQUAL  = 212;
-    const INVALID_DATE              = 213;
 
     /**
      * Exception to throw when an assertion failed.
@@ -543,23 +540,22 @@ public static function regex($value, $pattern, $message = null, $propertyPath =
      * @param int $length
      * @param string|null $message
      * @param string|null $propertyPath
-     * @param string $encoding
      * @return void
      * @throws \Assert\AssertionFailedException
      */
-    public static function length($value, $length, $message = null, $propertyPath = null, $encoding = 'utf8')
+    public static function length($value, $length, $message = null, $propertyPath = null)
     {
         static::string($value, $message, $propertyPath);
 
-        if (mb_strlen($value, $encoding) !== $length) {
+        if (grapheme_strlen($value) !== $length) {
             $message = sprintf(
                 $message ?: 'Value "%s" has to be %d exactly characters long, but length is %d.',
                 self::stringify($value),
                 $length,
-                mb_strlen($value, $encoding)
+                grapheme_strlen($value)
             );
 
-            $constraints = array('length' => $length, 'encoding' => $encoding);
+            $constraints = array('length' => $length);
             throw static::createException($value, $message, static::INVALID_LENGTH, $propertyPath, $constraints);
         }
     }
@@ -571,23 +567,22 @@ public static function length($value, $length, $message = null, $propertyPath =
      * @param int $minLength
      * @param string|null $message
      * @param string|null $propertyPath
-     * @param string $encoding
      * @return void
      * @throws \Assert\AssertionFailedException
      */
-    public static function minLength($value, $minLength, $message = null, $propertyPath = null, $encoding = 'utf8')
+    public static function minLength($value, $minLength, $message = null, $propertyPath = null)
     {
         static::string($value, $message, $propertyPath);
 
-        if (mb_strlen($value, $encoding) < $minLength) {
+        if (grapheme_strlen($value) < $minLength) {
             $message = sprintf(
                 $message ?: 'Value "%s" is too short, it should have more than %d characters, but only has %d characters.',
                 self::stringify($value),
                 $minLength,
-                mb_strlen($value, $encoding)
+                grapheme_strlen($value)
             );
 
-            $constraints = array('min_length' => $minLength, 'encoding' => $encoding);
+            $constraints = array('min_length' => $minLength);
             throw static::createException($value, $message, static::INVALID_MIN_LENGTH, $propertyPath, $constraints);
         }
     }
@@ -599,23 +594,22 @@ public static function minLength($value, $minLength, $message = null, $propertyP
      * @param integer $maxLength
      * @param string|null $message
      * @param string|null $propertyPath
-     * @param string $encoding
      * @return void
      * @throws \Assert\AssertionFailedException
      */
-    public static function maxLength($value, $maxLength, $message = null, $propertyPath = null, $encoding = 'utf8')
+    public static function maxLength($value, $maxLength, $message = null, $propertyPath = null)
     {
         static::string($value, $message, $propertyPath);
 
-        if (mb_strlen($value, $encoding) > $maxLength) {
+        if (grapheme_strlen($value) > $maxLength) {
             $message = sprintf(
                 $message ?: 'Value "%s" is too long, it should have no more than %d characters, but has %d characters.',
                 self::stringify($value),
                 $maxLength,
-                mb_strlen($value, $encoding)
+                grapheme_strlen($value)
             );
 
-            $constraints = array('max_length' => $maxLength, 'encoding' => $encoding);
+            $constraints = array('max_length' => $maxLength);
             throw static::createException($value, $message, static::INVALID_MAX_LENGTH, $propertyPath, $constraints);
         }
     }
@@ -628,35 +622,34 @@ public static function maxLength($value, $maxLength, $message = null, $propertyP
      * @param integer $maxLength
      * @param string|null $message
      * @param string|null $propertyPath
-     * @param string $encoding
      * @return void
      * @throws \Assert\AssertionFailedException
      */
-    public static function betweenLength($value, $minLength, $maxLength, $message = null, $propertyPath = null, $encoding = 'utf8')
+    public static function betweenLength($value, $minLength, $maxLength, $message = null, $propertyPath = null)
     {
         static::string($value, $message, $propertyPath);
 
-        if (mb_strlen($value, $encoding) < $minLength) {
+        if (grapheme_strlen($value) < $minLength) {
             $message = sprintf(
                 $message ?: 'Value "%s" is too short, it should have more than %d characters, but only has %d characters.',
                 self::stringify($value),
                 $minLength,
-                mb_strlen($value, $encoding)
+                grapheme_strlen($value)
             );
 
-            $constraints = array('min_length' => $minLength, 'encoding' => $encoding);
+            $constraints = array('min_length' => $minLength);
             throw static::createException($value, $message, static::INVALID_MIN_LENGTH, $propertyPath, $constraints);
         }
 
-        if (mb_strlen($value, $encoding) > $maxLength) {
+        if (grapheme_strlen($value) > $maxLength) {
             $message = sprintf(
                 $message ?: 'Value "%s" is too long, it should have no more than %d characters, but has %d characters.',
                 self::stringify($value),
                 $maxLength,
-                mb_strlen($value, $encoding)
+                grapheme_strlen($value)
             );
 
-            $constraints = array('max_length' => $maxLength, 'encoding' => $encoding);
+            $constraints = array('max_length' => $maxLength);
             throw static::createException($value, $message, static::INVALID_MAX_LENGTH, $propertyPath, $constraints);
         }
     }
@@ -668,22 +661,21 @@ public static function betweenLength($value, $minLength, $maxLength, $message =
      * @param string $needle
      * @param string|null $message
      * @param string|null $propertyPath
-     * @param string $encoding
      * @return void
      * @throws \Assert\AssertionFailedException
      */
-    public static function startsWith($string, $needle, $message = null, $propertyPath = null, $encoding = 'utf8')
+    public static function startsWith($string, $needle, $message = null, $propertyPath = null)
     {
         static::string($string, $message, $propertyPath);
 
-        if (mb_strpos($string, $needle, null, $encoding) !== 0) {
+        if (grapheme_strpos($string, $needle, null) !== 0) {
             $message = sprintf(
                 $message ?: 'Value "%s" does not start with "%s".',
                 self::stringify($string),
                 self::stringify($needle)
             );
 
-            $constraints = array('needle' => $needle, 'encoding' => $encoding);
+            $constraints = array('needle' => $needle);
             throw static::createException($string, $message, static::INVALID_STRING_START, $propertyPath, $constraints);
         }
     }
@@ -695,24 +687,23 @@ public static function startsWith($string, $needle, $message = null, $propertyPa
      * @param string $needle
      * @param string|null $message
      * @param string|null $propertyPath
-     * @param string $encoding
      * @return void
      * @throws \Assert\AssertionFailedException
      */
-    public static function endsWith($string, $needle, $message = null, $propertyPath = null, $encoding = 'utf8')
+    public static function endsWith($string, $needle, $message = null, $propertyPath = null)
     {
         static::string($string, $message, $propertyPath);
 
-        $stringPosition = mb_strlen($string, $encoding) - mb_strlen($needle, $encoding);
+        $stringPosition = grapheme_strlen($string) - grapheme_strlen($needle);
 
-        if (mb_strripos($string, $needle, null, $encoding) !== $stringPosition) {
+        if (grapheme_strripos($string, $needle, null) !== $stringPosition) {
             $message = sprintf(
                 $message ?: 'Value "%s" does not end with "%s".',
                 self::stringify($string),
                 self::stringify($needle)
             );
 
-            $constraints = array('needle' => $needle, 'encoding' => $encoding);
+            $constraints = array('needle' => $needle);
             throw static::createException($string, $message, static::INVALID_STRING_END, $propertyPath, $constraints);
         }
     }
@@ -724,22 +715,21 @@ public static function endsWith($string, $needle, $message = null, $propertyPath
      * @param string $needle
      * @param string|null $message
      * @param string|null $propertyPath
-     * @param string $encoding
      * @return void
      * @throws \Assert\AssertionFailedException
      */
-    public static function contains($string, $needle, $message = null, $propertyPath = null, $encoding = 'utf8')
+    public static function contains($string, $needle, $message = null, $propertyPath = null)
     {
         static::string($string, $message, $propertyPath);
 
-        if (mb_strpos($string, $needle, null, $encoding) === false) {
+        if (grapheme_strpos($string, $needle, null) === false) {
             $message = sprintf(
                 $message ?: 'Value "%s" does not contain "%s".',
                 self::stringify($string),
                 self::stringify($needle)
             );
 
-            $constraints = array('needle' => $needle, 'encoding' => $encoding);
+            $constraints = array('needle' => $needle);
             throw static::createException($string, $message, static::INVALID_STRING_CONTAINS, $propertyPath, $constraints);
         }
     }
@@ -1646,35 +1636,6 @@ public static function greaterOrEqualThan($value, $limit, $message = null, $prop
         }
     }
 
-    /**
-     * Assert that date is valid and corresponds to the given format.
-     *
-     * @param string      $value
-     * @param string      $format supports all of the options date(), except for the following:
-     *                            N, w, W, t, L, o, B, a, A, g, h, I, O, P, Z, c, r.
-     * @param string|null $message
-     * @param string|null $propertyPath
-     *
-     * @link http://php.net/manual/function.date.php#refsect1-function.date-parameters
-     */
-     public static function date($value, $format, $message = null, $propertyPath = null)
-     {
-         static::string($value, $message, $propertyPath);
-         static::string($format, $message, $propertyPath);
-
-         $dateTime = \DateTime::createFromFormat($format, $value);
-
-         if (false === $dateTime || $value !== $dateTime->format($format)) {
-             $message = sprintf(
-                 $message ?: 'Date "%s" is invalid or does not match format "%s".',
-                 self::stringify($value),
-                 self::stringify($format)
-             );
-
-             throw static::createException($value, $message, static::INVALID_DATE, $propertyPath, array('format' => $format));
-         }
-     }
-
     /**
      * Make a string version of a value.
      *
diff --git a/tests/Assert/Tests/AssertTest.php b/tests/Assert/Tests/AssertTest.php
index 0dba961c..ba41e56f 100644
--- a/tests/Assert/Tests/AssertTest.php
+++ b/tests/Assert/Tests/AssertTest.php
@@ -681,12 +681,6 @@ public function testLengthFailed()
         Assertion::length("asdf", 3);
     }
 
-    public function testLengthFailedForWrongEncoding()
-    {
-        $this->setExpectedException('Assert\AssertionFailedException', null, Assertion::INVALID_LENGTH);
-        Assertion::length("址", 1, null, null, 'ASCII');
-    }
-
     public function testLengthValidForGivenEncoding()
     {
         Assertion::length("址", 1, null, null, 'utf8');
@@ -1059,24 +1053,6 @@ public function invalidGreaterProvider()
         );
     }
 
-    /**
-     * @dataProvider validDateProvider
-     */
-    public function testValidDate($value, $format)
-    {
-        Assertion::date($value, $format);
-    }
-
-    public function validDateProvider()
-    {
-        return array(
-            array('2012-03-13', 'Y-m-d'),
-            array('29.02.2012 12:03:36.432563', 'd.m.Y H:i:s.u'),
-            array('13.08.2015 17:08:23 Thu Thursday th 224 August Aug 8 15 17 432563 UTC UTC', 'd.m.Y H:i:s D l S z F M n y H u e T'),
-            array('1439486158', 'U')
-        );
-    }
-
     /**
      * @dataProvider invalidGreaterProvider
      */
@@ -1117,24 +1093,6 @@ public function testGreaterOrEqualThanThrowsException($value, $limit)
         $this->setExpectedException('Assert\AssertionFailedException', null, Assertion::INVALID_GREATER_OR_EQUAL);
         Assertion::greaterOrEqualThan($value, $limit);
     }
-
-    /**
-     * @dataProvider invalidDateProvider
-     */
-    public function testInvalidDate($value, $format)
-    {
-        $this->setExpectedException('Assert\AssertionFailedException', null, Assertion::INVALID_DATE);
-        Assertion::date($value, $format);
-    }
-
-    public function invalidDateProvider()
-    {
-        return array(
-            array('this is not the date', 'Y-m-d'),
-            array('2011-02-29', 'Y-m-d'),
-            array('2012.02.29 12:60:36.432563', 'Y.m.d H:i:s.u')
-        );
-    }
 }
 
 class ChildStdClass extends \stdClass