The securing of data loading originating from an external device into a code memory area defined by an initial program of the secure element and any modification of which is controlled solely by the latter. When the external device obtains data to be transmitted to the secure element, the latter simulates an image of the code memory area as it would be modified by the loading of these data. A signature is calculated on the basis of the simulated image, then dispatched to the secure element with the data. The initial program of the secure element compares a signature that it has calculated over the whole of the code memory area after the actual loading of the data, with the signature received from the external device. The identity between these signatures ensures that the code memory area conforms to the image simulated by the external device, and is unimpaired.