Samba writes wrong file permissions

["Robert S" <robert.spam.me.senseless@gmail.com>]

I have the following in my smb.conf:

[public]
        path = /home/apache/files
        force user = www-data
        force group = www-data
        read only = No
        create mask = 0640
        force directory mode = 755
        guest ok = Yes

ls /home/apache/files/Dictation/XXXX/ -l
total 736
-rw-r----- 1 www-data www-data 318976 Jun  4 11:56 DS400039.DSS
-rw-r----- 1 www-data www-data 427520 Jun  4 13:32 DS400040.DSS
-rwxrwxrwx 1 www-data www-data    501 Jun  4 13:32 VoiceFolder.xml

I do not want to have world-writeable files.  How do I fix this?