Concepts: checking signatures of methods with arguments

I've been playing around with concepts. Here's a minimal example where I'm trying to create a concept based on method signatures: template concept bool myConcept() { return requires(T a, int i) { { a.foo() } -> int; { a.bar(i) } -> int; }; } struct Object { int foo() {return 0;} int bar(int) {return 0;} }; static_assert(myConcept(), "Object does not adhere to myConcept"); To my surprise writing { a.bar(int) } -> int did not work, so I resorted to adding an additional argument to the requires expression. This seems a bit strange and I was wondering if there is a way to do the same thing. Another thing that worked was using something like { a.bar((int)0) } -> int, but I find this worse.