diff --git a/lib/framework.php b/lib/framework.php
index 620730370f..3a62bb5d68 100644
--- a/lib/framework.php
+++ b/lib/framework.php
@@ -57,6 +57,10 @@ define('NOTICE_INBOX_SOURCE_FORWARD', 4);
 define('NOTICE_INBOX_SOURCE_PROFILE_TAG', 5);
 define('NOTICE_INBOX_SOURCE_GATEWAY', -1);
 
+define('URL_REGEX_VALID_PATH_CHARS',        '\pN\pL\,\!\(\)\.\:\-\_\+\/\=\&\;\%\~\*\$\+\'\@');
+define('URL_REGEX_VALID_QSTRING_CHARS',     URL_REGEX_VALID_PATH_CHARS);
+define('URL_REGEX_VALID_FRAGMENT_CHARS',    URL_REGEX_VALID_PATH_CHARS . '\?\#');
+
 // append our extlib dir as the last-resort place to find libs
 
 set_include_path(get_include_path() . PATH_SEPARATOR . INSTALLDIR . '/extlib/');
diff --git a/lib/util.php b/lib/util.php
index 05e3e732bd..977c55f4e6 100644
--- a/lib/util.php
+++ b/lib/util.php
@@ -1013,9 +1013,9 @@ function common_replace_urls_callback($text, $callback, $arg = null) {
         ')'.
         '(?:'.
             '(?:\:\d+)?'. //:port
-            '(?:/[\pN\pL$\,\!\(\)\.\:\-\_\+\/\=\&\;\%\~\*\$\+\'@]*)?'. // /path
-            '(?:\?[\pN\pL\$\,\!\(\)\.\:\-\_\+\/\=\&\;\%\~\*\$\+\'@\/]*)?'. // ?query string
-            '(?:\#[\pN\pL$\,\!\(\)\.\:\-\_\+\/\=\&\;\%\~\*\$\+\'\@/\?\#]*)?'. // #fragment
+            '(?:/['  . URL_REGEX_VALID_PATH_CHARS    . ']*)?'.  // path
+            '(?:\?[' . URL_REGEX_VALID_QSTRING_CHARS . ']*)?'.  // ?query string
+            '(?:\#[' . URL_REGEX_VALID_FRAGMENT_CHARS . ']*)?'. // #fragment
         ')(?<![\?\.\,\#\,])'.
     ')'.
     '#ixu';