The present disclosure is drawn to UV-curable inkjet inks, fluid sets, and printing systems. An example UV-curable inkjet ink can include water, a photo-initiator, from 8 wt % to 25 wt % organic co-solvent, and from 2 wt % to 20 wt % of a polyurethane. The polyurethane can include a polymer strand including a polymer backbone having two ends terminating at first and second capping units. The polymer backbone can be formed of polymerized monomers including a diisocyanate and a reactive diol selected from an acrylate-containing diol or a methacrylate-containing diol. The first capping unit can include an acrylate-containing monoalcohol, a methacrylate-containing monoalcohol, an allyl-containing monoalcohol, an allyl-containing monoamine, a styrene-containing monoalcohol, an acrylamide-containing monoalcohol, or a methacrylamide-containing monoalcohol reacted with an isocyanate group of the diisocyanate. The second capping unit can include 3-(cyclohexylamino)-1-propanesulfonic acid or 2-(cyclohexylamino)ethanesulfonic acid reacted with an isocyanate group of the diisocyanate.