Read-Host – accept valid path and filename only?

Good Morning,

I currently have this line:

Do {$Executable = Read-Host "What executable (including the path) do you want copy and run on the remote system"} Until (Test-Path $Executable)

How can I improve it so that it will only accept a valid path with a filename please? Like:

C:IE.exe

but not

C:

Thanks very much for any help you can provide.