The half-life of 171Tm was measured by gamma-ray spectrometry, using the reference source method. The measured point-like source was prepared by homogenous mixing of 44Ti with 171Tm in order to obtain an identical detection geometry for both nuclides. The half-life of 171Tm was determined by following the count-rate ratio between the gamma-ray emissions at 66.73 keV (171Tm) and 67.9/78.3 keV (44Ti). The measurement campaign consisted of 280 measurements acquired over a period of 449 days, corresponding to about 60% of the half-life value. The result for the 171Tm half-life, 702.4 (70) d, is consistent with the currently recommended value, however the uncertainty assessment of the latter is poorly documented.