Narrow-band observations fail to detect Lyα emission within a volume centred on the z= 2.168 quasar PKS 0424–131. This is in contrast to surveys of Lyα emitters in the field at similar redshifts and flux limits, which indicate that tens of sources should be visible within the same volume. The observed difference indicates that the quasar environment has a significant influence on the observed density of Lyα emitters. To quantify this effect, we have constructed a semi-analytic model to simulate the effect of a luminous quasar on nearby Lyα emitters. We find the null detection around PKS 0424–131 implies that the minimum isothermal temperature of Lyα emitter host haloes is greater than (68 per cent level), corresponding to a virial mass of ∼1.2 × 1012 M⊙. This indicates that the intense ultraviolet emission of the quasar may be suppressing the star formation in nearby galaxies. Our study illustrates that low-redshift quasar environments may serve as a surrogate for studying the radiative suppression of galaxy formation during the epoch of reionization.