Stephan Bonnar has failed his post-fight drug test for an anabolic steroid, according to a report by on Friday.

Bonnar lost to Anderson Silva in the main event of UFC 153 in October in Brazil.

Also, Dave Herman, who suffered a co-main event defeat to Antonio Rodrigo Nogueira, also failed his post-fight drug test. They were the lone fighters of the 24 on the card to do so. Herman’s test came back with traces of marijuana in his system.

For both Bonnar (15-8) and Herman (21-5) this is a second failed drug test. Bonnar, who announced his retirement from MMA earlier this week, also tested positive for a steroid following a loss to Forrest Griffin.

Herman’s previous failed test was a pre-fight one. It cancelled a planned bout with Mike Russow.