@@ -8,8 +8,9 @@
 %define sys.call syscall
 
 ; register order for syscall convention
 %define sys.reg.n 7
+%define sys.reg.ret rax
 %define sys.reg.0 rax
 %define sys.reg.1 rdi
 %define sys.reg.2 rsi
 %define sys.reg.3 rdx
@@ -18,8 +19,9 @@
 %define sys.reg.6 r9
 
 ; register order for ccall convention
 %define ccall.reg.ct 6
+%define ccall.reg.ret rdi
 %define ccall.reg.0 rdi
 %define ccall.reg.1 rsi
 %define ccall.reg.2 rdx
 %define ccall.reg.3 rcx