Rigid foldability is an important requirement when origami is used as the basis to design technical systems that consist of rigid materials. This paper presents a heuristic algorithm that adjusts the location of vertices of nonrigidly foldable but kinematically determinate crease patterns such that they become rigidly foldable. The adjustment is achieved by utilizing constraint violations that occur during the folding process of nonrigidly foldable configurations. The folding process is kinematically simulated through a robust simulator that is based on a bar and hinge principle. The benefits of the algorithm are showcased in different examples, including single-vertex as well as multi-vertex crease patterns.