diff --git a/system/core/Utf8.php b/system/core/Utf8.php
index 6ca1a02..98352db 100644
--- a/system/core/Utf8.php
+++ b/system/core/Utf8.php
@@ -73,14 +73,12 @@
 	 *
 	 * Ensures strings contain only valid UTF-8 characters.
 	 *
-	 * @uses	CI_Utf8::_is_ascii()	Decide whether a conversion is needed
-	 *
 	 * @param	string	$str	String to clean
 	 * @return	string
 	 */
 	public function clean_string($str)
 	{
-		if ($this->_is_ascii($str) === FALSE)
+		if ($this->is_ascii($str) === FALSE)
 		{
 			if (ICONV_ENABLED)
 			{
@@ -147,7 +145,7 @@
 	 * @param	string	$str	String to check
 	 * @return	bool
 	 */
-	protected function _is_ascii($str)
+	public function is_ascii($str)
 	{
 		return (preg_match('/[^\x00-\x7F]/S', $str) === 0);
 	}
diff --git a/tests/codeigniter/core/Utf8_test.php b/tests/codeigniter/core/Utf8_test.php
index 7129913..2cf4048 100644
--- a/tests/codeigniter/core/Utf8_test.php
+++ b/tests/codeigniter/core/Utf8_test.php
@@ -18,8 +18,8 @@
 
 	public function test_is_ascii()
 	{
-		$this->assertTrue($this->utf8->is_ascii_test('foo bar'));
-		$this->assertFalse($this->utf8->is_ascii_test('тест'));
+		$this->assertTrue($this->utf8->is_ascii('foo bar'));
+		$this->assertFalse($this->utf8->is_ascii('тест'));
 	}
 
 }
\ No newline at end of file
diff --git a/tests/mocks/core/utf8.php b/tests/mocks/core/utf8.php
index 30b78ad..c8214a6 100644
--- a/tests/mocks/core/utf8.php
+++ b/tests/mocks/core/utf8.php
@@ -13,9 +13,4 @@
 		defined('UTF8_ENABLED') OR define('UTF8_ENABLED', TRUE);
 	}
 
-	public function is_ascii_test($str)
-	{
-		return $this->_is_ascii($str);
-	}
-
 }
\ No newline at end of file
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index ca31669..bda4cba 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -505,6 +505,7 @@
 
       -  ``UTF8_ENABLED`` now requires only one of `Multibyte String <http://php.net/mbstring>`_ or `iconv <http://php.net/iconv>`_ to be available instead of both.
       -  Changed method ``clean_string()`` to utilize ``mb_convert_encoding()`` if it is available but ``iconv()`` is not.
+      -  Renamed method ``_is_ascii()`` to ``is_ascii()`` and made it public.
 
    -  Added `compatibility layers <general/compatibility_functions>` for PHP's `mbstring <http://php.net/mbstring>`_ (limited support) and `password <http://php.net/password>`_ extensions.
    -  Removed ``CI_CORE`` boolean constant from *CodeIgniter.php* (no longer Reactor and Core versions).