Partisans are poor judges of news content, rating neutral content as biased against their views (the hostile media perception) and forgiving biased content when it favors their side. This study tests whether a short news media literacy public service announcement (PSA) appearing before political programming can influence credibility and hostility ratings of the program and program host. Our findings suggest that a media literacy PSA can be effective, but its impact depends on the position of the news program and on the political ideology of the viewers. In this case, the media literacy PSA only influenced conservatives’ evaluations of the political program, improving perceptions of a neutral or congruent (conservative) host while further depressing ratings of an incongruent (liberal) host. Liberals’ evaluations of the program were unaffected by the PSA. Implications for media literacy messaging and information processing are discussed.