Can't see how to compile a header file with /clr switch in a mixed class

When creating a mixed mode class, on compilation the header file complains that it needs to be complied with the /clr switch开发者_JAVA百科 as it is a mixed mode class, however, I can't see any option to specifically compile that header with /clr from visual studio, and I don't want to set the entire project with a /clr flag,

Does anyone know how I can specify that this header file is compiled correctly with /clr?

Thanks in advance!

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Every cpp file that includes the header needs the /clr flag, not the header itself.