This paper characterizes a phenomenon I call ‘binarism grammatical lacuna’ (BGL). BGL occurs when non-binary sex and gender identities are forced to choose between being he or she by the grammar of a language owing to the sex/gender binary. Although hermeneutical injustice (HI) lies at its core, given that non-binary communities come up with hermeneutical devices to overcome unintelligibility and these tools are discredited, a variety of epistemic injustices, besides HI, intertwine in BGL. I address contributory injustice, pragmatic competence injustice, (...) testimonial injustice, and testimonial smothering. Section 1 introduces the phenomenon by portraying it as an ensemble of epistemic injustices. Section 2 elucidates the variety of HI at the core of BGL by examining the case of mainstream Spanish, and section 3 reveals it as producing the primary harm of HI. Section 4 studies the relationship between grammar, ideology, and language use, calling attention to the fact that grammatical lacunae are performatively reenacted in daily speech acts. Section 5 explores the agential dimension of BGL, examining responsibilities. In addition to addressing some of the forms of epistemic injustice that might intertwine in BGL besides HI, I portray non-marginalized users of binary grammar when addressing non-binary people as hermeneutical misfirers. (shrink)