Thanks for your great advice, soonix. I'm now working on installing, understanding and exploiting Strawberry. Since I don't get around much anymore I thought I'd just install the .MSI version of 5.10 but the installer issued the message "Installer is no longer responding" for an hour, so I had to give up. (I'll report this to them as soon as I have time to figure out their complicated reporting procedures.) So far I'm getting the same results whether I issue programname.pl or c:\perl programname.pl. In either case $] is set to 5.22, the version I'm trying to avoid. Is there any way my program can sense that it is running Strawberry Perl rather than ActiveState Perl?