We present accurate x-ray diffraction data at high pressures for AuIn₂, AuGa₂ and AuAl₂, obtained using a diamond anvil cell with the ELETTRA synchrotron source. The resulting P–V data obtained from the d-values were used to get the universal equation of state (UEOS), which is compared with theoretical estimates. Deviation from linearity is evident in the UEOS curves of AuIn₂ and AuGa₂, thus verifying that some of the observed anomalies in these systems below 5 GPa are due to electronic topological transitions.