The flexible storage bag includes overlaying first and second sidewalls defining an internal volume that can be accessed from an open top edge. To evacuate air from the internal volume after the open top edge has been closed, the bag includes a one-way valve element attached to the first sidewall and communicating with the internal volume. To prevent the one-way valve element from becoming clogged by the opposing second sidewall, the bag also includes a clearance member that maintains at least a partial clearance between the first and second sidewalls proximate the valve element. The clearance member can take many forms such as a textured portion on the second sidewall that includes evacuation passages which provide air in the internal volume access to the valve element, a permeable element covering the valve element, and a rigid or compressible structure that spaces the second sidewall from the valve element.