float comparison gives wrong result in loop?

[Bradley Smith]

With the following code, why does the assert fail?

import std.stdio;

void main() {
	const float STEP_SIZE = 0.2f;
	
	float j = 0.0f;
	while (j <= ( 1.0f / STEP_SIZE)) {
		j += 1.0f;
		writefln(j <= ( 1.0f / STEP_SIZE));
	}
	assert(!(j <= ( 1.0f / STEP_SIZE)));
}

The loop exits early, but it should not. The result of
"j <= ( 1.0f / STEP_SIZE)" is somehow different in the while statement 
versus in the call to writefln.

Interestingly, if the code is optimized, the assert passes.

Is this a bug?

Thanks,
   Bradley