Index: sites/all/modules/filefield/filefield.module
===================================================================
--- sites/all/modules/filefield/filefield.module	(revision 12888)
+++ sites/all/modules/filefield/filefield.module	(working copy)
@@ -731,7 +731,7 @@
   $errors = array();
 
   if (!empty($extensions)) {
-    $regex = '/\.('. ereg_replace(' +', '|', preg_quote($extensions)) .')$/i';
+    $regex = '/\.('. preg_replace('/ +/', '|', preg_quote($extensions)) .')$/i';
     $matches = array();
     if (preg_match($regex, $file->filename, $matches)) {
       $extension = $matches[1];