Priority of template constructor

I have the template class Foo:

template<class T>
class Foo {
public:
    Foo() = default;
    Foo(const Foo&) = default;
    Foo(Foo&&) = default;
    Foo& operator=(Foo&&) = default;
    Foo& operator=(const Foo&) = default;

    template<class U, typename = typename std::enable_if<
            !std::is_same<typename std::decay<U>::type, Foo>::value>::type>
    Foo(U&&) {

    }
};

int main() {
    Foo<int> ff;
    Foo<char> dd(ff); //here I want a compiler error
    Foo<int> e(15); //it should work
    return 0;
}

I'm trying to add constraints about template constructor, however this code compiles so I think I'm missing something, what's the proper way to add the enable_if?