A method includes providing a structure having two fins extending from a substrate; an isolation structure isolating bottom portions of the fins; source/drain (S/D) features over each of the fins; a dielectric fin oriented lengthwise parallel to the fins and disposed between the two fins and over the isolation structure; a dummy gate stack over the isolation structure, the fins, and the dielectric fin; and one or more dielectric layers over sidewalls of the dummy gate stack. The method further includes removing the dummy gate stack to result in a gate trench within the one or more dielectric layers, wherein the dielectric fin is exposed in the gate trench; trimming the dielectric fin to reduce a width of the dielectric fin; and after the trimming, forming a high-k metal gate in the gate trench.