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The M24 high-order finite-difference time-domain (FDTD) algorithm was upgraded to directly model irregularly shaped and perfectly conducting objects using locally conformed extended-stencil cells. This upgrade eliminates the need for hybrid M24/FDTD regions around perfect conductors and the consequent cross-algorithm numerical reflections. The recently developed simplified conformal approach, which affects cell conformity through exclusively adjusting its edge lengths, was used and judiciously applied to all three contours of the M24 update equation. This approach ensures stable numerical simulations at maximum time steps for any partial cell fill factor. Numerical experiments further demonstrated that this easy to-implement approach matches the geometric accuracy of the standard FDTD method while preserving the excellent high phase coherence advantage of the M24 algorithm.