This disclosure relates to a method for securing the execution of a program by a processor, including a comparison instruction for comparing two data items, followed by a program operation which is selected as a function of a comparison result provided by the comparison instruction. The method may include, before the execution of the comparison instruction, calculating in various ways comparison data representative of the equality of the data to be compared, after the execution of the comparison instruction, verifying whether the comparison data calculated are consistent with the fact that the program operation is selected or not selected, and activating an error signal if the comparison data are mutually inconsistent or inconsistent with the result of the comparison.