This paper describes a type system for JCop, which is an extension of Java with language mechanisms for context-oriented programming. A simple type system as in Java, however, is not sufficient to prevent errors due to the absence of invoked methods because interfaces of objects can change at run time by dynamic layer composition, a characteristic feature of context-oriented programming. Igarashi, Hirschfeld, and Masuhara have studied a type system for dynamic layer composition, but their type system is not directly applicable to JCop due to JCop-specific features such as layer inheritance, first-class layers, and declarative layer composition. We discuss how their type system can be extended to these language features.