Working with nullable types in Expression Trees

A type can be passed to the Expression.Constant function as a second argument. Something like typeof(int?) or, in the case of this question, column.Type.

e.g.

Expression.Constant(value, column.Type)

I had to convert the value type to the column type using Expression.Convert:

Expression where = Expression.GreaterThanOrEqual(column, Expression.Convert(Expression.Constant(value), column.Type));