© 2018 SPIE. Raman spectroscopy is an optical technique that can be used to evaluate the biomolecular composition of tissue and cell samples in a real-time and non-invasive manner. Subtle differences between datasets of spectra obtained from related cell groups can be identified using multivariate statistical algorithms. Such techniques are highly sensitive to small errors, however, and, therefore, the classification sensitivity of Raman spectroscopy can be significantly impacted by miscalibration of the optical system due to small misalignments of the optical elements and/or variation in ambient temperature. Wavenumber calibration is often achieved by recording the spectrum from a wavenumber reference standard, such as 4-acetamidophenol or benzene, which contains numerous sharp peaks in the fingerprint region. Here, we investigate a commercial polymer slide as a wavenumber reference standard for the calibration of Raman spectra. The Raman spectrum of this slide contains numerous sharp peaks in the fingerprint region. Unlike many other reference standards, the polymer slide is non-hazardous, has an indefinite lifetime, and is designed in the shape of a glass slide used for microscopy. We evaluate this reference in terms of accuracy and repeatability, and we compare with the established 4-Acetamidophenol wavenumber reference.