diff --git a/Alien/Package.pm b/Alien/Package.pm
index 3efbc2c..84c94c8 100644
--- a/Alien/Package.pm
+++ b/Alien/Package.pm
@@ -186,12 +186,12 @@ package was unpacked, it is time now to wipe out the temporary directory.
 sub DESTROY {
 	my $this=shift;
 
-	return if (defined $this->unpacked_tree || $this->unpacked_tree eq '');
+	return if (! defined $this->unpacked_tree || $this->unpacked_tree eq '');
 	# This should never happen, but it pays to check.
 	if ($this->unpacked_tree eq '/') {
 		die "alien internal error: unpacked_tree is set to `/'. Please file a bug report!";
 	}
-	system 'rm', '-rf', $this->unpacked_tree &&
+	system ('rm', '-rf', $this->unpacked_tree) &&
 		die "unable to delete temporary directory `".$this->unpacked_tree."`: $!";
 	$this->unpacked_tree('');	
 }
diff --git a/Alien/Package/Deb.pm b/Alien/Package/Deb.pm
index 2f38c9b..cdab7a9 100644
--- a/Alien/Package/Deb.pm
+++ b/Alien/Package/Deb.pm
@@ -61,6 +61,7 @@ Using dpkg-deb is a lot more future-proof, but the system may not have it.
 sub read_file {
 	my $this=shift;
 	$this->SUPER::read_file(@_);
+	my $file=$this->filename;
 
 	# Extract the control file from the deb file.
 	my @control;
@@ -164,6 +165,7 @@ Implment the unpack method to unpack a deb file.
 sub unpack {
 	my $this=shift;
 	$this->SUPER::unpack(@_);
+	my $file=$this->filename;
 
 	if ($this->have_dpkg_deb) {
 		system("dpkg-deb -x $file ".$this->unpacked_tree) &&