diff --git a/examples/echo_client.py b/examples/echo_client.py
index a4ae84e..8239b06 100644
--- a/examples/echo_client.py
+++ b/examples/echo_client.py
@@ -150,6 +150,11 @@ class EchoBot(ClientXMPP):
         try:
             encrypted = msg['omemo_encrypted']
             body = self['xep_0384'].decrypt_message(encrypted, mfrom, allow_untrusted)
+            # decrypt_message returns Optional[str]. It is possible to get
+            # body-less OMEMO message (see KeyTransportMessages), currently
+            # used for example to send heartbeats to other devices.
+            if body is None:
+                return None
             decoded = body.decode('utf8')
             if self.is_command(decoded):
                 await self.handle_command(mto, mtype, decoded)