Agricultural vehicle

An agricultural vehicle (1) has a driver cabin (2), means for supplying fresh air to the driver cabin (2) and an exhaust air path (27, 26, 18) from the driver cabin (2) into the open. The exhaust air path (27, 26, 18) comprises a check valve (22, 23) for preventing air flow from the open into the cabin, and the check valve (22, 23) has a rigid plate (22) for closing member.