[Solved]missing then statement?

Ok it's been a long time since I used Lua (learning ruby right now :P/>) so I'm rusty but can anyone tell me what's wrong with this script? I'm sure its something stupidly obvious I just can't figure it out.

for i=1,64 do
  turtle.placeUp()
  for j=1,5 do
	turtle.dig()
	turtle.forward()
	x = turtle.detectDown()
	if x = false then
	  turtle.select(2)
	  turtle.placeDown()
	  turtle.select(1)
	end
	turtle.digUp()
  end
end

The problem is at line 7 btw

On that line, use a double equal sign "==" instead of just one.

if x == false then

An alternative:

if not x then

Thanks, works now.