We investigate the effect of mechanical strain on the frequency of an electronic oscillator embedded in an integrated circuit. This analysis is aimed at explaining a 1% inaccuracy in the oscillator frequency under test conditions prescribed by a leading supplier of semi-conductor devices. During the test the package containing the oscillator was clamped to a circuit board by mechanical pressure. By considering the nature of the oscillator we show that tensile strains of the order of 10^-4 could explain the observations via the piezoresistance effect. Both a simple one-dimensional analysis based on the beam equation and an elastic finite element simulation show that strains of this magnitude can be generated during the test