As an additional note - the way you have it shown in the diagram puts the old brake fluid back into the master cyl. DO NOT DO THIS! EVER!
The stuff you get outta the lines is NOT to be reused. Brake fluid is not very expensive, but your life is - so is your car. Do not take chances with the brakes.
In fact, flush the entire system every year or so, replacing all the fluid with fresh new stuff (ask me how I know what happens when you don't! Hint - it involved a brake line that rusted through from the INSIDE due to moisture collecting in one spot)