How to declare a variable which can be set into a param of type std::chrono::milliseconds

I have the following method which intakes std::chrono::milliseconds

void SomeMethod(std::chrono::milliseconds some_value) {

  // some logic
}

I am able to call it in the following way:

using namespace std::chrono_literals;
SomeMethod(1000ms);

Works.
But, I want to call it in the following way by passing a member variable or some globally declared variable. Something like this,

using namespace std::chrono_literals;
std::chrono::system_clock::duration timeout = 3000ms;

But I get the following error:

error: no viable conversion from 'duration<[...], ratio<[...], 1000000>>' to 'duration<[...], ratio<[...], 1000>>'
SomeMethod(some_value);
                                                                             ^~~~~~~