Correction of B1 field non-uniformity is critical for quantitative MRI methods including fast macromolecular proton fraction (MPF) and variable flip angle T1 mapping. However, B1 mapping sequences increase the examination time and are not commonly available in clinics. A new algorithm is presented to enable simultaneous B1 correction in R1=1/T1 and MPF mapping without acquisition of B1 maps. The principle of the algorithm is based on different mathematical dependences of B1-related errors in R1 and MPF allowing extraction of a surrogate B1 map from uncorrected R1 and MPF maps. The method demonstrated excellent agreement with actual B1 mapping at 3T.