A writing utensil configurable between retracted and extended configurations. The writing utensil includes a body having an interior volume and an aperture. A reciprocally movable nib assembly is located in the body and includes a nib that, when in the extended configuration, traverses the aperture. To prevent the nib from drying when in the retracted configuration, a sealing element seals the aperture. In an embodiment, the sealing element is a resilient valve element that can be opened by a sleeve slidably engaging the nib assembly. After the sleeve opens the valve, the sleeve slides with respect to the nib assembly to expose the nib. In another embodiment, the sealing element can be a sliding door that is attached to the nib assembly and overlays the aperture. When the nib assembly is moved to the extended configuration, the sliding door slides in a manner that opens the aperture.