The paper extends the Shapiro-Stiglitz (1987) efficiency wage model by endogenising the probability of worker displacement as a function of the change in the firm's employment. This creates counter-cyclical variation in the wage mark-up and thereby generates real wage persistence. A New Keynesian DSGE model equipped with this extension replicates the empirical facts of a very limited response of the real wage to the business cycle together with a lagged hump-shaped response of employment to output.