Code_type/2: to_upper/to_lower bug?

33 ?- LowerCase = `a`, code_type(LowerCase,to_upper(Upper)).
LowerCase = [97],
Upper = 97.  # I would expect thiis to be 65

34 ?- LowerCase = `a`, code_type(LowerCase,to_lower(Lower)).
LowerCase = [97],
Lower = 65. # I would expect this to be 97

Am I missing something perhaps?
Please ignore this post, I just saw in the docs:

to_upper(Lower)
Char is an uppercase version of Lower. For non-letters, or letter without case, Char and Lower are the same. See also upcase_atom/2 and downcase_atom/2.