A barrier has an expandable width barrier having opposing first and second ends. A locking arm is pivotably coupled to the expandable width barrier at the first end and slidably coupled to the expandable width barrier at the second end. The locking arm may be an adjustable-length construction. The pivoting of the locking arm causes the barrier to move between locked and unlocked states. When the locking arm is pivoted to lock the barrier, it causes the barrier to linearly expand a supplemental amount and fits the barrier to opposing sides of a passageway opening.