Inhomogeneous B1 excitation impedes image quality, particularly at high field. Adiabatic pulse modulation ameliorates this effect, however super-adiabatic properties can be exploited to further improve performance. Spin Lock Adiabatic Correction (SLAC) pulses can be applied to any adiabatic pulse shape, through reduction of flip angle inaccuracies induced by B1 variability. In this work, SLAC is derived for BIR4 pulse shapes, and the superior performance of SLAC-BIR4 is demonstrated in both simulation and phantom experiments at 7T. The SLAC procedure is an attractive analytical alternative to numerical optimisation of adiabatic pulses.