diff --git a/man1/prtwash.1 b/man1/prtwash.1
index 4fca1ae..f794546 100644
--- a/man1/prtwash.1
+++ b/man1/prtwash.1
@@ -36,34 +36,28 @@ All items not included in the previous list WILL be deleted
 You can choose to delete some of the above by passing the proper
 option:
 .TP
-.B
--p
-also remove the built package (current version)
+.B \-p
+remove the built package (current version)
 .TP
-.B
--b
-also remove other built packages (older versions)
+.B \-b
+remove older builds (any package tarball that does NOT match
+the current version)
 .TP
-.B
--d
-also remove the add-on files provided by CRUX maintainers
+.B \-d
+remove add-on files provided by CRUX maintainers
 (patches and initscripts downloaded with \fBports -u\fP)
 .TP
-.B
--s
-also remove the upstream sources (those NOT obtained via \fBports -u\fP)
+.B \-s
+remove upstream sources (those NOT obtained via \fBports -u\fP)
 .TP
-.B
--t
+.B \-t
 (test mode) display the target files without deleting
 .TP
-.B
--q
+.B \-q
 (quiet mode) suppress messages about files that are kept;
 basically the same as \fBprtwash [OPTIONS] | grep -v "keeping"\fP
 .TP
-.B
--a
+.B \-a
 (automatic mode) take the port collections from the
 /etc/prt-get.conf file and do a recursive cleaning;
 if omitted, the command line must contain at least one <path> specifying
@@ -71,12 +65,14 @@ a valid port directory
 .PP
 Misc options
 .TP
-.B
--h
+.B \-\-parse\-pkgmk\-conf
+Revert to the v0.9 behaviour of parsing /etc/pkgmk.conf to determine the
+compression mode of built packages
+.TP
+.B \-h
 Display usage information
 .TP
-.B
--v
+.B \-v
 Display version
 .SH ENVIRONMENT
 In automatic mode, \fBprtwash\fP gets a list of repositories from
@@ -93,11 +89,24 @@ Sources under CRUX version control are only deleted if you pass the
 option \fB\-d\fP. Sources from upstream are only deleted if you pass the
 option \fB\-s\fP.
 .PP
-The current version of the package is only deleted if you pass the
-option \fB\-p\fP. Older versions of the package are only deleted if you
-pass the option \fB\-b\fP. Note that if the compression mode defined
-in /etc/pkgmk.conf has been changed since you last built the package,
-\fBprtwash\fP will not recognize the tarball in its regexp search.
+You can also delete the built package (current version) by passing
+the option \fB\-p\fP. To select only older versions for deletion,
+pass the option \fB\-b\fP instead. These two options operate independently,
+allowing you to target four distinct subsets (including the empty set)
+for deletion.
+.PP
+By passing the option \fB\-\-parse\-pkgmk\-conf\fP, you can modify the behaviour
+of the pattern matching performed to detect built packages. By default, the
+regexp searches are done with the patterns
+.B /${name}#${version}.*.pkg.tar.(gz|lz|xz|bz2)/
+and
+.B /${name}#.*pkg.tar.(gz|lz|xz|bz2)/
+using the variables defined in the \fBPkgfile\fP(5). Passing the option
+.B \-\-parse\-pkgmk\-conf
+will result in a more narrow regexp search, allowing the deletion of any package
+tarball that uses a different compression algorithm than the one currently defined
+in /etc/pkgmk.conf (which is how the v0.9 bash script worked).
+
 .SH COMPARISON WITH OTHER UTILITIES
 Because \fBprtwash\fP reads the location of port collections from \fB/etc/prt-get.conf\fP(5),
 you can easily control which collections are cleaned in automatic mode by commenting
diff --git a/scripts/prtwash.pl b/scripts/prtwash.pl
index a0d3e46..95077bc 100755
--- a/scripts/prtwash.pl
+++ b/scripts/prtwash.pl
@@ -18,7 +18,7 @@ our @portdirs;
 our $argports;
 my $version = 1.2.1;
 our %options = ( oldver=>0, pkgtoo=>0, srctoo=>0, addons=>0,
-  dryrun=>0, auto=>0, quiet=>0 );
+  dryrun=>0, auto=>0, quiet=>0, parse_pkgmk=>0 );
 
 ####################   main routine   ################################
 parse_args();
@@ -46,9 +46,8 @@ if ($options{auto} == 1) {
 
 ####################   subroutines   #################################
 sub parse_args {
-  while ( my $arg = pop(@ARGV) ) {
-  next if (-f $arg); # no filenames, only directories and options
- if ($arg eq "-b") {
+  foreach my $arg (@ARGV) {
+  if ($arg eq "-b") {
     $options{oldver} = 1;
    } elsif ($arg eq "-p") {
     $options{pkgtoo} = 1;
@@ -62,11 +61,16 @@ sub parse_args {
     $options{auto} = 1;
    } elsif ($arg eq "-q") {
     $options{quiet} = 1;
+   } elsif ($arg eq "--parse-pkgmk-conf") {
+    $options{parse_pkgmk} = 1;
    } elsif ($arg eq "-v") {
     print "$version\n";
     exit(0);
-   } elsif (-d $arg) {
+   } elsif ((-d $arg) ||          # false for symlink to a portdir, so a
+           (-f "$arg/Pkgfile")) { # followup test is performed to catch those
     push (@portdirs, $arg);
+   } elsif (-f $arg) {
+    print "WARN: ignoring invalid port directory $arg\n";
    } else {
     print_usage();
    }
@@ -124,7 +128,7 @@ sub parse_pkgfile {
   return \$name, \$version, \$release, \@source, \@renames;
 }
 
-sub keeplist { # remember to pop off the last element for regex purposes
+sub keeplist { # remember to pop off the last two elements for regex purposes
   my $port = shift;
   my @keepers = ("Pkgfile",".footprint",".signature");
     push (@keepers,"pre-install","post-install","README","README.md",
@@ -140,7 +144,7 @@ sub keeplist { # remember to pop off the last element for regex purposes
   my $i; my $si; my $ki;
   ENTRY: for ($i=0; $i<=$#source; $i++) {
     $si = $source[$i];
-    $ki = ($renames[$i] eq "SKIP" or $renames[$i] eq "") ? basename($si) :
+    $ki = ("$renames[$i]" eq "SKIP" or "$renames[$i]" eq "") ? basename($si) :
      $renames[$i];
     if ($si =~ /^remote:/) {
       next ENTRY if ($options{srctoo}==1);
@@ -150,21 +154,23 @@ sub keeplist { # remember to pop off the last element for regex purposes
       push(@keepers, $ki);
     }
   }
-  push (@keepers, $name.'#'.$version.'-'.$release.".pkg.tar.$compression_mode") if $options{pkgtoo}==0;
-  push (@keepers, $name."#.*pkg.tar.$compression_mode");
+  push (@keepers, "$name#$version.*\.pkg\.tar\.$compression_mode");
+  push (@keepers, "$name#.*\.pkg\.tar\.$compression_mode");
   return @keepers;
 }
 
 sub get_compress {
-  my $conf = "/etc/pkgmk.conf";
-  $compression_mode = "gz";
-  open(CONFIG,$conf) or return $compression_mode;
-  while(<CONFIG>) {
-    $compression_mode = $1 if m/^[\t ]*PKGMK_COMPRESSION_MODE=(.*)\n/;
+  my $suffix = "(gz|lz|xz|bz2)";
+  if ($options{parse_pkgmk} == 1) {
+    my $conf = "/etc/pkgmk.conf";
+    open(CONFIG,$conf) or return $suffix;
+      while(<CONFIG>) {
+        $suffix = $1 if m/^[\t ]*PKGMK_COMPRESSION_MODE=(.*)\n/;
+      }
+    close(CONFIG);
+    $suffix =~ s/"//g;          # ensure no double-quotes remain (thanks jaeger)
   }
-  close(CONFIG);
-  $compression_mode =~ s/"//g;  # ensure no double-quotes remain (thanks jaeger)
-  return $compression_mode;
+  return $suffix;
 }
 
 sub do_wash {
@@ -174,16 +180,18 @@ sub do_wash {
     print "WARN: no Pkgfile found in $port. Skipping.\n";
     return;
   } else {
-    my @keepers = keeplist($port);
-    my $nevermatch = "ReallyLongStringThatWouldNeverMatchAnyBuiltPackage";
-    my $pkgrex = pop(@keepers);
-    $pkgrex = ($options{oldver} == 1 or $options{pkgtoo} == 1) ? $nevermatch : $pkgrex;
+    my @keepers = keeplist($port); my $iswanted;
+    my $allbuilds = pop(@keepers);
+    my $currbuild = pop(@keepers);
 
     opendir (DIR,$port) or return;
+    print "=====> washing $port\n" unless $options{quiet} == 1;
     foreach my $f (sort(readdir(DIR))) {
       next if ($f eq '.' or $f eq '..');
       $f =~ s/\+/\\\+/g; # plus sign in filenames interferes with regex search
-      if ((grep /$f/, @keepers) or ($f =~ /$pkgrex/)) {
+      $iswanted = ( grep (/$f/, @keepers ) >= 1 );
+      if ($iswanted or ($options{pkgtoo}==0)*($f =~ /$currbuild/)
+     or ($options{oldver}==0)*($f =~ /$allbuilds/)*($f !~ /$currbuild/)) {
         print "... keeping file $port/$f.\n" unless $options{quiet} == 1;
       } else {
         remove ("$port/$f");
@@ -194,8 +202,7 @@ sub do_wash {
 }
 
 sub getportdirs { # returns scalar references to two arrays
-  my @basedirs;
-  my @localports;
+  my @basedirs; my @localports;
   my $conf = "/etc/prt-get.conf";
 
   open(PORTS, $conf) or die "could not open $conf";
@@ -211,7 +218,7 @@ sub getportdirs { # returns scalar references to two arrays
         push @basedirs, $line if (-d $line);
       } else {
         my @a = split(/:/, $line);
-        my @b = split(/,/, @a[1]);
+        my @b = split(/,/, $a[1]);
         while ( my $c = pop @b ) {
         my $port = $a[0] . "/" . $c;
           push @localports, $port if (-d $port);