An endoscopic forceps includes a housing having a shaft attached thereto that supports a pair of jaws disposed at a distal end thereof. A drive assembly having a drive shaft with a proximal end is operable to move the jaws relative to one another from an open to closed positions. A knife assembly is operable to advance a knife through tissue disposed between the jaws and includes a flange disposed thereon. A knife lockout is included that has a flange configured to engage the proximal end of the drive shaft and a lockout arm configured to engage the flange of the knife assembly to prevent movement thereof. Movement of the jaws to the closed position causes the proximal end of the drive shaft to engage the flange on the lockout which causes the lockout arm to disengage the flange on the knife assembly to permit advancement of the knife.