We give a simplified proof of the complex inversion formula for semigroups and, more generally, solution families for scalar-type Volterra equations, including the stronger versions on unconditional martingale differences (UMD) spaces. Our approach is based on (elementary) Fourier analysis.2000 Mathematics subject classification: 34G10, 43A50, 44A10, 47A60, 47D03, 47D06, 47D09.