Locking to a fringe of a tilt-tuned etalon provides a simple, inexpensive method for stabilizing tunable lasers. Here, we describe the use of such a system to stabilize an external-cavity quantum cascade laser; the locked laser has an Allan deviation of approximately 1 MHz over a one-second integration period, and has a single-scan tuning range of approximately 0.4 cm(-1). The system is robust, with minimal alignment requirements and automated lock acquisition, and can be easily adapted to different wavelength regions or more stringent stability requirements with minor alterations.