Existing quantum Hall interferometers measure twice the braiding phase, $e^{i2\theta}$, of Abelian anyons, i.e. the phase accrued when one quasi-particle encircles another clockwise. We propose a modified Fabry-P\'{e}rot or Mach-Zehnder interferometer that can measure $e^{i\theta}$. Comment: 3.5 pages, 2 figures