Single address Avalon MM slave

If I only have one single 32-bit register to write, I still must use address: STD_LOGIC_VECTOR(0 DOWNTO 0), which actually spans 2 32-bit words. Ideally, I would write:

...

IF avs_write = '1' THEN -- Address not used. Only writable register.

reg <= avs_data(2 DOWNTO 0); -- Only three bits are needed

go <= '1'; -- Write with side-effects!

END IF;

...

but now the condition must be:

IF avs_write = '1' AND avs_address = "0" THEN...

to avoid false triggering of signal 'go', apart from the fact that my memcpy() to an area of, say, 32 peripherals takes twice as long as needed.