Win32 assembly hello messagebox

_hello.asm

global _mainCRTStartup
extern _ExitProcess@4
extern _MessageBoxA@16  ; Value after @ is size of args on stack
section .text

_mainCRTStartup:

    ; Setup stack to give us 4 bytes to play with
    ;   push ebp
    ;   sub esp, 4 

    ; MessageBoxA( NULL, str_message, "", 0 );
        push 0
        push str_empty
        push str_message
        push 0
        call _MessageBoxA@16

    ; ExitProcess( 0 );
        push 0
        call _ExitProcess@4

section .data

str_message  db  "Hello world", 0
str_empty    db  0

build.ps1

# https://yasm.tortall.net/Download.html
.\yasm-1.3.0-win64.exe -fwin32 .\hello.asm

&"C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\link.exe" `
    /OUT:hello.exe `
    # Replace with whatever Windows SDK path
    /LIBPATH:"C:\Program Files (x86)\Windows Kits\10\Lib\10.0.17763.0\um\x86" `
    /MACHINE:X86 `
    /SUBSYSTEM:CONSOLE `
    kernel32.lib user32.lib `
    hello.obj