This article uses a unique dataset from the September 2019 municipal elections in St. Petersburg in order to examine empirically the efficacy of strategic voting under authoritarianism, as manifest in the effects of the "smart vote campaign" of Alexei Navalny in Russia. The analysis allows for the conclusion that the campaign, while technically similar to the vote advice applications that are now widespread in many democracies, was efficient enough to make a significant difference in the overtly authoritarian context. We demonstrate empirically that Navalny's call for strategic voting did indeed affect the behavior of the electorate, particularly by improving strategic coordination among opposition-minded voters; that the electoral results of the candidates backed by the "smart vote" campaign tended to be better than the electoral results of other non-United Russia candidates; and that as a result of the "smart vote" campaign, the dominant party's electoral results deteriorated quite visibly.