Methods for forming a single fin fin-like field effect transistor (FinFET) device are disclosed. An exemplary method includes providing a main mask layout and a trim mask layout to form fins of a fin-like field effect transistor (FinFET) device, wherein the main mask layout includes a first masking feature and the trim mask layout includes a second masking feature that defines at least two fins, the first masking feature and the second masking feature having a spatial relationship; and modifying the main mask layout based on the spatial relationship between the first masking feature and the second masking feature, wherein the modifying the main mask layout includes modifying the first masking feature such that a single fin FinFET device is formed using the modified main mask layout and the trim mask layout.