-my $image_ppm = ($ENV{TMPDIR} ? $ENV{TMPDIR} : "/tmp") . "/webcollage." . $$;
-my $image_tmp1 = $image_ppm . "-1";
-my $image_tmp2 = $image_ppm . "-2";
+my $image_ppm = sprintf ("%s/webcollage-%08x",
+ ($ENV{TMPDIR} ? $ENV{TMPDIR} : "/tmp"),
+ rand(0xFFFFFFFF));
+my $image_tmp1 = sprintf ("%s/webcollage-1-%08x",
+ ($ENV{TMPDIR} ? $ENV{TMPDIR} : "/tmp"),
+ rand(0xFFFFFFFF));
+my $image_tmp2 = sprintf ("%s/webcollage-2-%08x",
+ ($ENV{TMPDIR} ? $ENV{TMPDIR} : "/tmp"),
+ rand(0xFFFFFFFF));