GetTempFileName mangles path

[BoscoBilly]

Hi.
I'm using GetTempFileName to store a DL-ed file to
be decrypted.
The command line decrypter I am using does not like the following path returned by GetTempFileName:

C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\nsk601.tmp

Is there a way to force a correct path, not this mangled version?
Thx.
BB