diff --git a/DBus-service.md b/DBus-service.md
index 46e0088..1f07743 100644
--- a/DBus-service.md
+++ b/DBus-service.md
@@ -129,7 +129,13 @@ Example if you started the daemon without the optional USERNAME (exports all loc
 
 Keep in mind that if you use DBus as a system service and want to send a message using the dbus daemon, you must use `--system` instead of `--session` in the dbus send command.
 
-For an example of sending a group message through the dbus interface, see [#272](https://github.com/AsamK/signal-cli/issues/272).
+The groupId is handled as an array of bytes rather than a Base64 string. (See [#272](https://github.com/AsamK/signal-cli/issues/272).)
+
+The byte array can be obtained from a base64-encoded string (which looks like ixZI93QgqmjNpM8V+E25== and can be found in signal-cli's config file, by default in ~/.local/share/signal-cli/data/<PHONE_NUMBER>). To decode it to byte array, can use python:
+
+```
+python3 -c 'import base64; print(",".join(str(i) for i in base64.b64decode(b"ixZI93QgqmjNpM8V+E25==")))'
+```
 
 In the examples above, attachments are identified by the first `array:string:` argument (`dbus-send` arguments must be in the correct order). The last argument can either be a single `string:RECIPIENT` (as in the examples above) or an `array:string:RECIPIENT1,RECIPIENT2,...` (for `dbus-send`, an array argument consists of a comma-separated list).