%macro def 1.nolist
%define %1 38
%endmacro

%macro def2 1.nolist
%define _%1 38
%endmacro

def SMAC	; works as expected (unless SMAC already defined)
def SMAC	; does not work, because the mmacro implicitly fully expands %1

def2 SMAC	; this is the workaround, which works (even multiple times)
def2 SMAC	;  but defines the smacro _SMAC, not SMAC