call_user_func problem

Prior to 4.0.6 it worked fine, however, now when I try: $result = call_user_func("foo", &$bar); function foo( &$bar ) { $bar .= 'foobar'; return 1; } I get this: Warning: Call-time pass-by-reference has been deprecated - argument passed by value; If you would like to pass it by reference, modify the declaration of call_user_func(). If you would like to enable call-time pass-by-reference, you can set allow_call_time_pass_reference to true in your INI file. However, future versions may not support this any longer. Does that mean I can't pass by reference anymore? I kinda need to (the two functions above are not my actual functions btw).... Thanks.