function without "this" cannot be const?

[Shriramana Sharma via Digitalmars-d-learn]

I'm trying to interface to a C function:

extern(C) const char * textAttrN(const char * specString, size_t n);

and getting the error:

Error: function <src>.textAttrN without 'this' cannot be const

Please advise as to what I'm doing wrong?! :-(

-- 
Shriramana Sharma, Penguin #395953