Some Russian nouns of the third declension have a specialized “second locative” form with the stressed desinence -и. By contrast, the otherwise homophonous genitive, dative and “plain” locative forms of these nouns are believed to have stress on the stem, cf. genitive, dative and “plain” locative те́ни, vs. second locative (в) тени́ ‘(in) the shade’. However, the data from the poetic texts available in the Russian National Corpus indicate that some of the relevant nouns display accentual variation in their genitive and dative forms. This variation statistically reflects semantic contrasts: in particular, nouns denoting substances (грязь ‘dirt’, пыль ‘dust’, кровь ‘blood’) tend to have stress on the desinence -и in contexts denoting fixed attachment or immersion in the substance. Semanticization of these accentual constrasts is arguably triggered by analogy with the locative forms. These findings indicate a nascent feature of +/- attachment, which cross-cuts case paradigms of at least some Russian nouns.