A package-integrated, compact, low-cost, athermal wavelength locker is introduced. It uses a novel etalon material, Schnaelite, to reduce environmental temperature sensitivity well over an order of magnitude compared to commercially available fused silica based lockers. Thermo-optical properties of temperature insensitive etalons are presented. Results demonstrating frequency stability of devices incorporating Schnaelite etalon based discriminators show optical frequency shifts below 1 GHz for large changes in case and laser temperature. This enabling technology promotes future small form-factor, low power consumption, multichannel laser sources.