diff --git a/lib/util.php b/lib/util.php
index c0c9801116..03e3618db8 100644
--- a/lib/util.php
+++ b/lib/util.php
@@ -394,20 +394,20 @@ function common_render_text($text)
 
 function common_replace_urls_callback($text, $callback) {
     // Start off with a regex
-    $regex = '#
-    (?:
-        (?:
-            (?:https?|ftps?|mms|rtsp|gopher|news|nntp|telnet|wais|file|prospero|webcal|xmpp|irc)://
-            |
-            (?:mailto|aim|tel):
-        )
-        [^.\s]+\.[^\s]+
-        |
-        (?:[^.\s/:]+\.)+
-        (?:museum|travel|[a-z]{2,4})
-        (?:[:/][^\s]*)?
-    )
-    #ix';
+    $regex = '#'.
+    '(?:'.
+        '(?:'.
+            '(?:https?|ftps?|mms|rtsp|gopher|news|nntp|telnet|wais|file|prospero|webcal|xmpp|irc)://'.
+            '|'.
+            '(?:mailto|aim|tel):'.
+        ')'.
+        '[^.\s]+\.[^\s]+'.
+        '|'.
+        '(?:[^.\s/:]+\.)+'.
+        '(?:museum|travel|[a-z]{2,4})'.
+        '(?:[:/][^\s]*)?'.
+    ')'.
+    '#ix';
     preg_match_all($regex, $text, $matches);
 
     // Then clean up what the regex left behind