Does adding enumerators into a `enum class` break ABI?

This is pretty much the same question as Does adding enumerators into enum break ABI?, but with enum class introduced by C++11.

For what I understand by this page I can simply have a stable ABI by defining an underlying type for my enumerative:

enum class Foo : uint32_t
{
    x, y, z
}

I would say this works fine, as for instance something like

enum class Foo : uint8_t { x = 257 }

Will not compile.

Am I correct?