0 terminated?

The following code outputs the first two letters of a file called test.txt.
test.txt has the letters abcd and nothing else in it.
When I display the ab with StdOut there is no error message but I have cause to wonder... shouldn't that string be null terminated?
Should I be manually placing a 0 at the end of it?

  .486
  .model flat, stdcall
  option casemap :none

  include \masm32\include\windows.inc
  include \masm32\macros\macros.asm

  include \masm32\include\masm32.inc
  include \masm32\include\gdi32.inc
  include \masm32\include\user32.inc
  include \masm32\include\kernel32.inc.

  includelib \masm32\lib\masm32.lib
  includelib \masm32\lib\gdi32.lib
  includelib \masm32\lib\user32.lib
  includelib \masm32\lib\kernel32.lib

  .data    
    filename db "c:\masm32\assembly projects\fopen\test.txt",0    
    file_handle HANDLE ?
    file_buffer DWORD 256 dup (?)
    readC DW ?
  .code

start:
  invoke CreateFile,ADDR filename,GENERIC_READ,FILE_SHARE_READ,
                      NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL
  mov file_handle,eax
  invoke ReadFile,file_handle,ADDR file_buffer,sizeof(BYTE)*2,ADDR readC,NULL
  invoke StdOut,ADDR file_buffer
  invoke CloseHandle,file_handle

  exit
end start

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