diff --git a/utils.py b/utils.py
index 314d898..2f19936 100644
--- a/utils.py
+++ b/utils.py
@@ -212,7 +212,9 @@ class ServiceBot():
         cmd = cmd_args[0].lower()
         cmd_args = cmd_args[1:]
         if cmd not in self.commands:
-            self.reply(irc, 'Error: Unknown command %r.' % cmd)
+            if not cmd.startswith('\x01'):
+                # Ignore invalid command errors from CTCPs.
+                self.reply(irc, 'Error: Unknown command %r.' % cmd)
             log.info('(%s/%s) Received unknown command %r from %s', irc.name, self.name, cmd, irc.getHostmask(source))
             return