Query Editor / M code for subtracting one day

Hi,

I have the below code in M that gives the number of days between the start date and end date (it works fine):

[EndDate]-[StartDate]

But if I try to subtract "1" then I get an error:

[EndDate]-[StartDate]-1

I assume it's because [EndDate] and [StartDate] are stored as dates but "1" is an integar? Please do you know how to fix?

Thanks,

CM