Typescript does not recognize that the generic parameters match

In the following code typescript complains that the argument does not match the called function.

In general that is ok, but in this case the type of emailType and args are bound to the same generic type T so it should not error. As you can see in the following lines, if you fix the type T to some concrete value, e.g. "Foo" typescript correctly recognizes that the types match.

• Is there either a way to tell typescript that the types match (without a as any assertion)?
• Do you know of a better pattern to this problem? I really like it, because it makes calling sendMail convenient as you have intellisense for the emailType, which makes it easy to see which emails are available, and then intellisense for the required data to send the email.

const mails = {
  Foo: (args: { foo: string }) => "",
  Bar: (args: { bar: string }) => "",
}

function sendMail<T extends keyof typeof mails>(emailType: T, args: Parameters<typeof mails[T]>[0]){
  mails[emailType](args) // ERROR: Argument of type '{ foo: string; } | { bar: string; }' is not assignable to parameter of type '{ foo: string; } & { bar: string; }'
  mails[emailType as "Foo"](args as Parameters<typeof mails["Foo"]>[0]) // works
  mails[emailType as "Bar"](args as Parameters<typeof mails["Bar"]>[0]) // works
}