diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index bc8135a1b4..d238e3c0b9 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -441,7 +441,18 @@ function xmlrpc_removepostdata( $content ) {
  */
 function wp_extract_urls( $content ) {
 	preg_match_all(
-		"#((?:[\w-]+://?|[\w\d]+[.])[^\s()<>]+[.](?:\([\w\d]+\)|(?:[^`!()\[\]{};:'\".,<>?«»“”‘’\s]|(?:[:]\d+)?/?)+))#",
+		"#("
+			. "(?: ([\w-]+:)?//? )"
+			. "[^\s()<>]+"
+			. "[.]"
+			. "(?:"
+				. "\([\w\d]+\) |"
+				. "(?:"
+					. "[^`!()\[\]{};:'\".,<>?«»“”‘’\s] |"
+					. "(?: [:]\d+ )?/?"
+				. ")+"
+			. ")"
+		. ")#x",
 		$content,
 		$post_links
 	);