Our previous research showed that Russian children commit fewer gender-agreement errors with diminutive nouns than with their simplex counterparts. Experiment 1 replicates this finding with Russian children (N=24, mean 3;7, range 2;10–4;6). Gender agreement was recorded from adjective usage as children described animal pictures given just their names, varying in derivational status (diminutive/simplex), novelty, and gender. Experiment 2 extends the gender-agreement elicitation methodology developed for Russian to Serbian, a language with similar morphosyntactic structure but considerably fewer diminutives in child-directed speech. Serbian children (N=22, mean age 3;8, range 3;0–4;1), exhibited an advantage for diminutive nouns of almost the same magnitude as the Russian children. The fact that the diminutive advantage was found in a language with a low frequency of diminutives in the input suggests that morphophonological homogeneity of word clusters and membership in dense neighbourhoods are important factors that contribute to the reduction of inflectional errors during language development.