require/3 compatibility

I'm trying to switch over from Gnu emacs-21.3 to Xemacs-21.4.19.

Many lisp files contain code that looks like:

(require 'thingatpt nil t)

This works in emacs-21.3, but in Xemacs-21.4.19, I get the message:
Wrong number of arguments: require, 3

21.3 has a built-in require:
require is a built-in function.
(require FEATURE &optional FILENAME NOERROR)

If feature FEATURE is not loaded, load it from FILENAME.
If FEATURE is not a member of the list `features', then the feature
is not loaded; so load the file FILENAME.
If FILENAME is omitted, the printname of FEATURE is used as the file name,
and `load' will try to load this name appended with the suffix `.elc',
`.el' or the unmodified name, in that order.
If the optional third argument NOERROR is non-nil,
then return nil if the file is not found instead of signaling an error.
Normally the return value is FEATURE.
The normal messages at start and end of loading FILENAME are suppressed.

Xemacs-21.4.19 has:
`require' is a built-in function
(require FEATURE &optional FILENAME)

Documentation:
If feature FEATURE is not loaded, load it from FILENAME.
If FEATURE is not a member of the list `features', then the feature
is not loaded; so load the file FILENAME.
If FILENAME is omitted, the printname of FEATURE is used as the file name.

What do I need to to to get this to work?

Thanks,
Steve
.

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