Wide character in warn at /usr/bin/makeinfo

I'm running makeinfo on some Russian docs (for maxima) and I get the message

Wide character in warn at /home/toy/bin/makeinfo line 637.
Introduction.texi:207: @ref reference to nonexistent node `Category:
Справка' (possibly involving @category)

What does this mean?  Is it something I need to fix?

(The bad ref to the nonexistent node is something I still have to fix of
course.)

-- 
Ray