Use constrain properly

[lbussy]

As written, the way constrain is used has no effect/unintended effect and will generate the following warnings:

warning: second operand of conditional expression has no effect [-Wunused-value]
warning: third operand of conditional expression has no effect [-Wunused-value]

This change addresses those warnings and corrects the behavior.

[tablatronix]

Thanks, no idea why I thought it was edit by reference, been using php too much lately.. lol

[lbussy]

I stared at it for a while wondering what was wrong. Looked legit to me as well.