diff --git a/plugins/zfs/zfs_usage_ b/plugins/zfs/zfs_usage_
index fdd5b3a9..e44caf12 100755
--- a/plugins/zfs/zfs_usage_
+++ b/plugins/zfs/zfs_usage_
@@ -160,6 +160,9 @@ sub do_collect {
 
     foreach my $line (split(/\n/, `$fsget` )) {
         my ($name, $key, $value, undef ) = (split(/\t/,$line));
+        # try to preserve underscores:
+        #   * duplicate existing ones
+        #   * afterwards replace slashs with single ones
         ($name =~ s/_/__/g);
         ($name =~ s/\//_/g);
         $filesystems->{$name}->{$key}=$value;
@@ -170,6 +173,9 @@ sub do_collect {
 sub do_config_fs {
     my ($fs) = @_;
     my $fs_slash = ($fs);
+    # try to restore underscores (see "do_collect" for the reverse operation):
+    #   * substitute all underscores with slashs
+    #   * afterwards transform *double* slashs back into a single underscore
     ($fs_slash =~ s/_/\//g);
     ($fs_slash =~ s/\/\//_/g);