diff --git a/src/Stringy.php b/src/Stringy.php
index 97c6a6d..cc962c9 100644
--- a/src/Stringy.php
+++ b/src/Stringy.php
@@ -383,13 +383,7 @@ class Stringy implements \Countable, \IteratorAggregate, \ArrayAccess
      */
     public function collapseWhitespace()
     {
-        $regexEncoding = mb_regex_encoding();
-        mb_regex_encoding($this->encoding);
-
-        $str = mb_ereg_replace('[[:space:]]+', ' ', $this->str);
-        mb_regex_encoding($regexEncoding);
-
-        return self::create($str, $this->encoding)->trim();
+        return $this->regexReplace('[[:space:]]+', ' ')->trim();
     }
 
     /**
@@ -1267,17 +1261,7 @@ class Stringy implements \Countable, \IteratorAggregate, \ArrayAccess
      */
     public function replace($search, $replacement)
     {
-        $regexEncoding = mb_regex_encoding();
-        mb_regex_encoding($this->encoding);
-
-        // Don't want the args being parsed as regex
-        $search = preg_quote($search);
-        $replacement = preg_quote($replacement);
-
-        $str = mb_ereg_replace($search, $replacement, $this->str);
-        mb_regex_encoding($regexEncoding);
-
-        return self::create($str, $this->encoding);
+        return $this->regexReplace(preg_quote($search), $replacement);
     }
 
     /**
diff --git a/tests/CommonTest.php b/tests/CommonTest.php
index b4285db..21399ea 100644
--- a/tests/CommonTest.php
+++ b/tests/CommonTest.php
@@ -835,6 +835,8 @@ abstract class CommonTest extends PHPUnit_Framework_TestCase
             array('foo', '', '', 'foo'),
             array('foo', '\s', '\s', 'foo'),
             array('foo bar', 'foo bar', '', ''),
+            array('foo bar', 'foo bar', 'f(o)o', '\1'),
+            array('\1 bar', 'foo bar', 'foo', '\1'),
             array('bar', 'foo bar', 'foo ', ''),
             array('far bar', 'foo bar', 'foo', 'far'),
             array('bar bar', 'foo bar foo bar', 'foo ', ''),
@@ -853,6 +855,7 @@ abstract class CommonTest extends PHPUnit_Framework_TestCase
         return array(
             array('', '', '', ''),
             array('bar', 'foo', 'f[o]+', 'bar'),
+            array('o bar', 'foo bar', 'f(o)o', '\1'),
             array('bar', 'foo bar', 'f[O]+\s', '', 'i'),
             array('foo', 'bar', '[[:alpha:]]{3}', 'foo'),
             array('', '', '', '', 'msr', 'UTF-8'),