I need to add a 32-bit number to a 48-bit number. What I want to do is perform the first 32 bit arithmetic in C as follows: Wv.A += Wv.B ; And to propagate the carry to the most significant word as follows: __asm { ADDC WORD Wv+10,#0 } Unfortunately I get on compilation the following error: error C195: inline-asm: Invalid instruction operand(s) Apparently the identifier Wv is not known by the compiler though it is known in C expressions and similar assembler statements are generated by the compiler when I select a SRC output of the compiler. Is someone familiar with inline assembly? Thanks