This invention relates to a method (and a corresponding terminal) of detecting a presence of a circuit extending arrangement inserted between a physical interface, connected to a terminal, and a smart card, the physical interface being adapted to receive the smart card, the method comprising the steps of measuring at least one electrical characteristic of the physical interface, and determining whether a circuit extending arrangement, changing at least one characteristic of said physical interface, is coupled to said physical interface on the basis said measurement.In this way, simple and efficient detection of a tampering/spy circuit is provided.