diff --git a/change_log.txt b/change_log.txt
index 2a092f79..e55598be 100644
--- a/change_log.txt
+++ b/change_log.txt
@@ -5,6 +5,7 @@
 - changed unloadFilter() to not return a boolean in favor of chaining and API conformity
 - bugfix unregisterObject() raised notice when object to unregister did not exist
 - changed internals to use Smarty::$_MBSTRING ($_CHARSET, $_DATE_FORMAT) for better unit testing
+- added Smarty::$_UTF8_MODIFIER for proper PCRE charset handling (Forum Topic 20452)
 
 17.12.2011
 - improvement of compiling speed by new handling of plain text blocks in the lexer/parser (issue 68)
diff --git a/libs/Smarty.class.php b/libs/Smarty.class.php
index 6f72b49d..b129aa97 100644
--- a/libs/Smarty.class.php
+++ b/libs/Smarty.class.php
@@ -61,9 +61,15 @@ if (!defined('SMARTY_MBSTRING')) {
 }
 if (!defined('SMARTY_RESOURCE_CHAR_SET')) {
     // UTF-8 can only be done properly when mbstring is available!
+    /**
+     * @deprecated in favor of Smarty::$_CHARSET
+     */
     define('SMARTY_RESOURCE_CHAR_SET', SMARTY_MBSTRING ? 'UTF-8' : 'ISO-8859-1');
 }
 if (!defined('SMARTY_RESOURCE_DATE_FORMAT')) {
+    /**
+     * @deprecated in favor of Smarty::$_DATE_FORMAT
+     */
     define('SMARTY_RESOURCE_DATE_FORMAT', '%b %e, %Y');
 }
 
@@ -166,12 +172,25 @@ class Smarty extends Smarty_Internal_TemplateBase {
      * contains directories outside of SMARTY_DIR that are to be muted by muteExpectedErrors()
      */
     public static $_muted_directories = array();
-    
+    /**
+     * Flag denoting if Multibyte String functions are available
+     */
     public static $_MBSTRING = SMARTY_MBSTRING;
+    /**
+     * The character set to adhere to (e.g. "UTF-8")
+     */
     public static $_CHARSET = SMARTY_RESOURCE_CHAR_SET;
+    /**
+     * The date format to be used internally
+     * (accepts date() and strftime())
+     */
     public static $_DATE_FORMAT = SMARTY_RESOURCE_DATE_FORMAT;
+    /**
+     * Flag denoting if PCRE should run in UTF-8 mode
+     */
     public static $_UTF8_MODIFIER = 'u';
     
+    
     /**#@+
      * variables
      */
@@ -1437,7 +1456,7 @@ class Smarty extends Smarty_Internal_TemplateBase {
     }
 }
 
-// let PREG treat strings as ISO-8859-1 if we're not dealing with UTF-8
+// let PCRE (preg_*) treat strings as ISO-8859-1 if we're not dealing with UTF-8
 if (Smarty::$_CHARSET !== 'UTF-8') {
     Smarty::$_UTF8_MODIFIER = '';
 }
diff --git a/libs/plugins/block.textformat.php b/libs/plugins/block.textformat.php
index 93f8a52b..b22b104a 100644
--- a/libs/plugins/block.textformat.php
+++ b/libs/plugins/block.textformat.php
@@ -84,7 +84,7 @@ function smarty_block_textformat($params, $content, $template, &$repeat)
             continue;
         }
         // convert mult. spaces & special chars to single space
-        $_paragraph = preg_replace(array('!\s+!u', '!(^\s+)|(\s+$)!u'), array(' ', ''), $_paragraph);
+        $_paragraph = preg_replace(array('!\s+!' . Smarty::$_UTF8_MODIFIER, '!(^\s+)|(\s+$)!' . Smarty::$_UTF8_MODIFIER), array(' ', ''), $_paragraph);
         // indent first line
         if ($indent_first > 0) {
             $_paragraph = str_repeat($indent_char, $indent_first) . $_paragraph;
diff --git a/libs/plugins/function.html_checkboxes.php b/libs/plugins/function.html_checkboxes.php
index 42513691..fb9584bb 100644
--- a/libs/plugins/function.html_checkboxes.php
+++ b/libs/plugins/function.html_checkboxes.php
@@ -177,7 +177,7 @@ function smarty_function_html_checkboxes_output($name, $value, $output, $selecte
     
     if ($labels) {
         if ($label_ids) {
-            $_id = smarty_function_escape_special_chars(preg_replace('![^\w\-\.]!u', '_', $name . '_' . $value));
+            $_id = smarty_function_escape_special_chars(preg_replace('![^\w\-\.]!' . Smarty::$_UTF8_MODIFIER, '_', $name . '_' . $value));
             $_output .= '<label for="' . $_id . '">';
         } else {
             $_output .= '<label>';
diff --git a/libs/plugins/function.html_radios.php b/libs/plugins/function.html_radios.php
index 12deb421..7c830724 100644
--- a/libs/plugins/function.html_radios.php
+++ b/libs/plugins/function.html_radios.php
@@ -165,7 +165,7 @@ function smarty_function_html_radios_output($name, $value, $output, $selected, $
     
     if ($labels) {
         if ($label_ids) {
-            $_id = smarty_function_escape_special_chars(preg_replace('![^\w\-\.]!u', '_', $name . '_' . $value));
+            $_id = smarty_function_escape_special_chars(preg_replace('![^\w\-\.]!' . Smarty::$_UTF8_MODIFIER, '_', $name . '_' . $value));
             $_output .= '<label for="' . $_id . '">';
         } else {
             $_output .= '<label>';
diff --git a/libs/plugins/function.mailto.php b/libs/plugins/function.mailto.php
index c61cf2df..55d5c060 100644
--- a/libs/plugins/function.mailto.php
+++ b/libs/plugins/function.mailto.php
@@ -130,7 +130,7 @@ function smarty_function_mailto($params, $template)
         }
         $address_encode = '';
         for ($x = 0, $_length = strlen($address); $x < $_length; $x++) {
-            if (preg_match('!\w!u', $address[$x])) {
+            if (preg_match('!\w!' . Smarty::$_UTF8_MODIFIER, $address[$x])) {
                 $address_encode .= '%' . bin2hex($address[$x]);
             } else {
                 $address_encode .= $address[$x];
diff --git a/libs/plugins/modifier.capitalize.php b/libs/plugins/modifier.capitalize.php
index d264f049..a78e3632 100644
--- a/libs/plugins/modifier.capitalize.php
+++ b/libs/plugins/modifier.capitalize.php
@@ -30,17 +30,17 @@ function smarty_modifier_capitalize($string, $uc_digits = false, $lc_rest = fals
             $upper_string = mb_convert_case( $string, MB_CASE_TITLE, Smarty::$_CHARSET );
         } else {
             // uppercase word breaks
-            $upper_string = preg_replace("!(^|[^\p{L}'])([\p{Ll}])!ueS", "stripslashes('\\1').mb_convert_case(stripslashes('\\2'),MB_CASE_UPPER, '" . addslashes(Smarty::$_CHARSET) . "')", $string);
+            $upper_string = preg_replace("!(^|[^\p{L}'])([\p{Ll}])!eS" . Smarty::$_UTF8_MODIFIER, "stripslashes('\\1').mb_convert_case(stripslashes('\\2'),MB_CASE_UPPER, '" . addslashes(Smarty::$_CHARSET) . "')", $string);
         }
         // check uc_digits case
         if (!$uc_digits) {
-            if (preg_match_all("!\b([\p{L}]*[\p{N}]+[\p{L}]*)\b!u", $string, $matches, PREG_OFFSET_CAPTURE)) {
+            if (preg_match_all("!\b([\p{L}]*[\p{N}]+[\p{L}]*)\b!" . Smarty::$_UTF8_MODIFIER, $string, $matches, PREG_OFFSET_CAPTURE)) {
                 foreach($matches[1] as $match) {
                     $upper_string = substr_replace($upper_string, mb_strtolower($match[0], Smarty::$_CHARSET), $match[1], strlen($match[0]));
                 }
             } 
         }
-        $upper_string = preg_replace("!((^|\s)['\"])(\w)!ue", "stripslashes('\\1').mb_convert_case(stripslashes('\\3'),MB_CASE_UPPER, '" . addslashes(Smarty::$_CHARSET) . "')", $upper_string);
+        $upper_string = preg_replace("!((^|\s)['\"])(\w)!e" . Smarty::$_UTF8_MODIFIER, "stripslashes('\\1').mb_convert_case(stripslashes('\\3'),MB_CASE_UPPER, '" . addslashes(Smarty::$_CHARSET) . "')", $upper_string);
         return $upper_string;
     }
     
@@ -49,16 +49,16 @@ function smarty_modifier_capitalize($string, $uc_digits = false, $lc_rest = fals
         $string = strtolower($string);
     }
     // uppercase (including hyphenated words)
-    $upper_string = preg_replace("!(^|[^\p{L}'])([\p{Ll}])!ueS", "stripslashes('\\1').ucfirst(stripslashes('\\2'))", $string); 
+    $upper_string = preg_replace("!(^|[^\p{L}'])([\p{Ll}])!eS" . Smarty::$_UTF8_MODIFIER, "stripslashes('\\1').ucfirst(stripslashes('\\2'))", $string); 
     // check uc_digits case
     if (!$uc_digits) {
-        if (preg_match_all("!\b([\p{L}]*[\p{N}]+[\p{L}]*)\b!u", $string, $matches, PREG_OFFSET_CAPTURE)) {
+        if (preg_match_all("!\b([\p{L}]*[\p{N}]+[\p{L}]*)\b!" . Smarty::$_UTF8_MODIFIER, $string, $matches, PREG_OFFSET_CAPTURE)) {
             foreach($matches[1] as $match) {
                 $upper_string = substr_replace($upper_string, strtolower($match[0]), $match[1], strlen($match[0]));
             }
         } 
     }
-    $upper_string = preg_replace("!((^|\s)['\"])(\w)!ue", "stripslashes('\\1').strtoupper(stripslashes('\\3'))", $upper_string);
+    $upper_string = preg_replace("!((^|\s)['\"])(\w)!e" . Smarty::$_UTF8_MODIFIER, "stripslashes('\\1').strtoupper(stripslashes('\\3'))", $upper_string);
     return $upper_string;
 } 
 
diff --git a/libs/plugins/modifier.spacify.php b/libs/plugins/modifier.spacify.php
index f7985add..a907232f 100644
--- a/libs/plugins/modifier.spacify.php
+++ b/libs/plugins/modifier.spacify.php
@@ -21,7 +21,7 @@
 function smarty_modifier_spacify($string, $spacify_char = ' ')
 {
     // well… what about charsets besides latin and UTF-8?
-    return implode($spacify_char, preg_split('//u', $string, -1, PREG_SPLIT_NO_EMPTY));
+    return implode($spacify_char, preg_split('//' . Smarty::$_UTF8_MODIFIER, $string, -1, PREG_SPLIT_NO_EMPTY));
 } 
 
 ?>
\ No newline at end of file
diff --git a/libs/plugins/modifier.truncate.php b/libs/plugins/modifier.truncate.php
index d1eabd19..9a803ec9 100644
--- a/libs/plugins/modifier.truncate.php
+++ b/libs/plugins/modifier.truncate.php
@@ -32,7 +32,7 @@ function smarty_modifier_truncate($string, $length = 80, $etc = '...', $break_wo
         if (mb_strlen($string, Smarty::$_CHARSET) > $length) {
             $length -= min($length, mb_strlen($etc, Smarty::$_CHARSET));
             if (!$break_words && !$middle) {
-                $string = preg_replace('/\s+?(\S+)?$/u', '', mb_substr($string, 0, $length + 1, Smarty::$_CHARSET));
+                $string = preg_replace('/\s+?(\S+)?$/' . Smarty::$_UTF8_MODIFIER, '', mb_substr($string, 0, $length + 1, Smarty::$_CHARSET));
             } 
             if (!$middle) {
                 return mb_substr($string, 0, $length, Smarty::$_CHARSET) . $etc;
diff --git a/libs/plugins/modifiercompiler.count_characters.php b/libs/plugins/modifiercompiler.count_characters.php
index f7a8dd26..98e8efa0 100644
--- a/libs/plugins/modifiercompiler.count_characters.php
+++ b/libs/plugins/modifiercompiler.count_characters.php
@@ -21,7 +21,7 @@
 function smarty_modifiercompiler_count_characters($params, $compiler)
 {
     if (!isset($params[1]) || $params[1] != 'true') {
-        return 'preg_match_all(\'/[^\s]/u\',' . $params[0] . ', $tmp)';
+        return 'preg_match_all(\'/[^\s]/' . Smarty::$_UTF8_MODIFIER . '\',' . $params[0] . ', $tmp)';
     }
     if (Smarty::$_MBSTRING) {
         return 'mb_strlen(' . $params[0] . ', \'' . addslashes(Smarty::$_CHARSET) . '\')';
diff --git a/libs/plugins/modifiercompiler.count_sentences.php b/libs/plugins/modifiercompiler.count_sentences.php
index 7f48a3ec..2f517be9 100644
--- a/libs/plugins/modifiercompiler.count_sentences.php
+++ b/libs/plugins/modifiercompiler.count_sentences.php
@@ -22,7 +22,7 @@
 function smarty_modifiercompiler_count_sentences($params, $compiler)
 {
     // find periods, question marks, exclamation marks with a word before but not after.
-    return 'preg_match_all("#\w[\.\?\!](\W|$)#uS", ' . $params[0] . ', $tmp)';
+    return 'preg_match_all("#\w[\.\?\!](\W|$)#S' . Smarty::$_UTF8_MODIFIER . '", ' . $params[0] . ', $tmp)';
 }
 
 ?>
\ No newline at end of file
diff --git a/libs/plugins/modifiercompiler.count_words.php b/libs/plugins/modifiercompiler.count_words.php
index ce97c658..e05738c0 100644
--- a/libs/plugins/modifiercompiler.count_words.php
+++ b/libs/plugins/modifiercompiler.count_words.php
@@ -21,9 +21,9 @@
 function smarty_modifiercompiler_count_words($params, $compiler)
 {
     if (Smarty::$_MBSTRING) {
-        // return 'preg_match_all(\'#[\w\pL]+#u\', ' . $params[0] . ', $tmp)';
+        // return 'preg_match_all(\'#[\w\pL]+#' . Smarty::$_UTF8_MODIFIER . '\', ' . $params[0] . ', $tmp)';
         // expression taken from http://de.php.net/manual/en/function.str-word-count.php#85592
-        return 'preg_match_all(\'/\p{L}[\p{L}\p{Mn}\p{Pd}\\\'\x{2019}]*/u\', ' . $params[0] . ', $tmp)';
+        return 'preg_match_all(\'/\p{L}[\p{L}\p{Mn}\p{Pd}\\\'\x{2019}]*/' . Smarty::$_UTF8_MODIFIER . '\', ' . $params[0] . ', $tmp)';
     }
     // no MBString fallback
     return 'str_word_count(' . $params[0] . ')';
diff --git a/libs/plugins/modifiercompiler.strip.php b/libs/plugins/modifiercompiler.strip.php
index 2a2d9d0e..f1d5db04 100644
--- a/libs/plugins/modifiercompiler.strip.php
+++ b/libs/plugins/modifiercompiler.strip.php
@@ -27,7 +27,7 @@ function smarty_modifiercompiler_strip($params, $compiler)
     if (!isset($params[1])) {
         $params[1] = "' '";
     }
-    return "preg_replace('!\s+!u', {$params[1]},{$params[0]})";
+    return "preg_replace('!\s+!" . Smarty::$_UTF8_MODIFIER . "', {$params[1]},{$params[0]})";
 }
 
 ?>
\ No newline at end of file
diff --git a/libs/plugins/shared.mb_wordwrap.php b/libs/plugins/shared.mb_wordwrap.php
index c65d63f9..ba3498c7 100644
--- a/libs/plugins/shared.mb_wordwrap.php
+++ b/libs/plugins/shared.mb_wordwrap.php
@@ -22,7 +22,7 @@ if(!function_exists('smarty_mb_wordwrap')) {
     function smarty_mb_wordwrap($str, $width=75, $break="\n", $cut=false)
     {
         // break words into tokens using white space as a delimiter
-        $tokens = preg_split('!(\s)!uS', $str, -1, PREG_SPLIT_NO_EMPTY + PREG_SPLIT_DELIM_CAPTURE);
+        $tokens = preg_split('!(\s)!S' . Smarty::$_UTF8_MODIFIER, $str, -1, PREG_SPLIT_NO_EMPTY + PREG_SPLIT_DELIM_CAPTURE);
         $length = 0;
         $t = '';
         $_previous = false;
@@ -37,14 +37,14 @@ if(!function_exists('smarty_mb_wordwrap')) {
                 $length = 0;
 
                 if ($cut) {
-                    $_tokens = preg_split('!(.{' . $width . '})!uS', $_token, -1, PREG_SPLIT_NO_EMPTY + PREG_SPLIT_DELIM_CAPTURE);
+                    $_tokens = preg_split('!(.{' . $width . '})!S' . Smarty::$_UTF8_MODIFIER, $_token, -1, PREG_SPLIT_NO_EMPTY + PREG_SPLIT_DELIM_CAPTURE);
                     // broken words go on a new line
                     $t .= $break;
                 }
             }
 
             foreach ($_tokens as $token) {
-                $_space = !!preg_match('!^\s$!uS', $token);
+                $_space = !!preg_match('!^\s$!S' . Smarty::$_UTF8_MODIFIER, $token);
                 $token_length = mb_strlen($token, Smarty::$_CHARSET);
                 $length += $token_length;