================================================================================ P9501 J.A. Hillebrand & H.P. Korver "A well-formedness checker for muCRL" We present an algebraic specification for the static semantics of the process language $\mu$CRL. This specification can be executed in the ASF+SDF meta-environment which automatically derives a rewriting system for it. In this way, we immediately obtain a prototype of an enriched type checker (well-formedness checker) for $\mu$CRL. Our prototype is rather efficient and shows that automatic prototyping of formal specifications is feasible.