Int64 that accepts nulls? C# MVC [duplicate]

This question already has an answer here:

• C# DBNull and nullable Types - cleanest form of conversion 8 answers


• Object cannot be cast from DBNull to other types error shown? 5 answers

I have this variable receiveing data from an Excel:

var employeeCedula = Convert.ToInt64(employeeRow[OverheadReportStructure.Employees.Cedula]);

but when I debug the program it shows me the error "Object cannot be cast from DBNull to other types"

How can I change that line to accept nulls?