diff --git a/omnibot/bot.py b/omnibot/bot.py
index 450447b..c6abeee 100644
--- a/omnibot/bot.py
+++ b/omnibot/bot.py
@@ -190,6 +190,8 @@ class Bot:
         log.trace("%s", message)
         channel = message.parameters[0]
         who = message.prefix
+        if not who:
+            return
         if who.nick == self.server_config.nick:
             # Don't raise on_message events for ourselves
             return