Hex integers in Maxima 5.10

    I would like to work with integers to base 16, both in inout and
output, under Maxima 5.10. To that effect I set obase to 16 and ibase
to 16, in this order. The problem is, how do I specify a hex integer
on input? The help text for ibase says that for bases greater than 10
(and less than 35) one should use the capital letters of the alphabet.
However, Maxima seems to interpret input like that as variables:

(%i6) 2^ABC ;
                                      ABC
(%o6)                         2

or as some operator:


(%i8) 122ABC7DE ;
Incorrect syntax: ABC7DE is not an infix operator
122ABC7DE
                   ^
(%i8)

    Any ideas?