Abstract: Safety device for quick-fit attachments comprising two parts (1) and (2), of which one (1) is borne by the arm of the digger while the other (2) is secured to the tool (for example a dipper), said first part having a cradle (3) formed by a pair of hooks, able to grasp hold of a shaft (4) belonging to the second part in order to raise the tool and allow the first part to pivot so that the two parts can be pressed against one another to allow for locking, characterized in that each part of the attachment has a member (7) able to collaborate with a member (8) of the other part if the weight of the tool being picked up does not exceed the capacity of the digger, collaboration being impossible when such is not the case, so that the first part is unable to be pressed against the second and locking is prevented.