mod_irc does not set username correctly

I have ejabberd 2.1.5-3 installed on Debian Squeeze.
I registered in IRC module with Service Discovery and set

my username to: speckius

connection parameters to:
[{"irc.run.net","utf-8",6660,[]}].

Then I use the login form. And end up connected to IRC server as paul@example.com (paul is the nickname), not speckius@example.com.

I see no errors in ejabberd.log. How can I set the IRC username properly?