<b><i>Background:</i></b> When introducing new equipment or reference equations into the lung function laboratory, systematic <i>z</i>-score deviations could arise due to local differences in population or equipment. <b><i>Objective:</i></b> To propose a workable method for aligning reference equations with lung function equipment. <b><i>Method:</i></b> Using two cases of equipment transition in our laboratory as a test case, we first performed lung function testing after the transition, on a control group of 40 normal young adults (20 male/20 female; 20–30 years old). For those indices with an average <i>z</i>-score in excess of ±0.5, adapted reference values were obtained by an offset or scaling factor on the M coefficient with the so-called lambda-mu-sigma (LMS) method recommended by the Global Lung Function Initiative, and the <i>z</i>-scores were computed again. <b><i>Results:</i></b> Following a transition involving instrumental dead space reduction, the lung clearance index was predictably reduced, resulting in a mean (±SD) <i>z</i>-score of –1.9 (±1.1) in the control group; by adapting the reference values with an offset on M, the <i>z</i>-score became –0.1 (±1.1). Applying the same method to a transition of standard lung function equipment, the <i>z</i>-scores became centered around zero in the control group, but also became properly aligned in a test group of 81 other subjects spanning a wider age range (20–80 years). <b><i>Conclusions:</i></b> We proposed and verified a method for aligning local equipment with reference values obtained elsewhere, or following a local change in equipment. The key is to measure a relatively small young adult group, identifying those lung function indices that need adaptation based on <i>z</i>-scores, in order to then obtain laboratory-specific reference values that can be applied over the entire age range.