diff --git a/btrbk b/btrbk
index 38ca470..75a7b95 100755
--- a/btrbk
+++ b/btrbk
@@ -2075,28 +2075,24 @@ sub system_read_raw_info_dir($)
 }
 
 
-sub system_write_raw_info($$)
+sub system_write_raw_info($$;@)
 {
   my $vol = shift // die;
   my $raw_info = shift // die;
-
+  my %opts = @_;
+  my $append = $opts{append};
   my $info_file = $vol->{PATH} . '.info';
-  my @line;
-  push @line, "#btrbk-v$VERSION";
-  push @line, "# Do not edit this file";
 
   # sort by %raw_info_sort, then by key
-  foreach(sort { (($raw_info_sort{$a} || 99) <=> ($raw_info_sort{$b} || 99)) || ($a cmp $b) } keys %$raw_info) {
+  my @line = $append ? () : ("#btrbk-v$VERSION", "# Do not edit this file");
+  foreach(sort { (($raw_info_sort{$a} // 99) <=> ($raw_info_sort{$b} // 99)) || ($a cmp $b) } keys %$raw_info) {
     push @line, ($_ . '=' . $raw_info->{$_});
   }
 
-  DEBUG "Creating raw info file " . ($raw_info->{INCOMPLETE} ? "(incomplete)" : "(complete)") . ": $info_file";
-  my $echo_text = (join '\n', @line);
-  TRACE "DUMP INFO_FILE=$info_file\n" . join("\n", @line) if($do_trace);
-
+  DEBUG "Writing (" . ($append ? "append:" . join(",", keys %$raw_info) : "create") . ") raw info file: $info_file";
   my $ret = run_cmd(
     { cmd => [ 'echo', '-e', '-n', '"' . (join '\n', @line) . '\n"' ] },
-    { redirect_to_file => { unsafe => $info_file },
+    { ($append ? "append_to_file" : "redirect_to_file") => { unsafe => $info_file },
       rsh => vinfo_rsh($vol),
     });
   return undef unless(defined($ret));