How should I return an int from a stored procedure in entity framework 4.1?

I am using Entity Framework 4.1 and do sometimes need to call stored procedures. Some of these return ints as return values. For instance

CREATE PROCEDURE ...
...
INSERT INTO ...
SELECT @@Identity

(Update: removed return value, not relevant. We're returning the identity)

I have the following code in my respository class:

var orderNo = context.Database.SqlQuery<int>("EXEC myProc").Single();

This fails with the error message The specified cast from a materialized 'System.Decimal' type to the 'System.Int32' type is not valid.

If I change the code above to

var orderNo = context.Database.SqlQuery<decimal>("EXEC myProc").Single();

everything works.

Now, I think that I should be able to return an int. What's the proper way to do this?