The present invention relates to a theft-deterrent device which is intended for attachment to theft-attractive articles and which includes a first element (1) which is provided with a connecting unit (5) that projects out from the first element. The connecting unit is intended to be inserted through the article to be protected. The article is locked to the device by attaching and locking the connecting unit to a second element (2). The first element includes a fragile marking substance container (6) which is broken or crushed when an attempt is made to release the elements from each other, so as to release a marking substance contained in the container and therewith render the article unusable. The first element includes a base element (4) which has the form of a one-piece structure and which includes a recess (7) having an opening through which the container (6) can be inserted into the recess. The connecting unit (5) can is insertably arranged in the base element and is constructed to hold the container in the recess.