TypeScript Version: 2.2.1

Code

function f(param : object) {
    for (let key in param) {

    }
}

f({'a' : 2});

Expected behavior:
Code compiles, I expect object to be of "object type".
Actual behavior:
TypeScript Error error TS2407: The right-hand side of a 'for...in' statement must be of type 'any', an object type or a type parameter.