Tamper-proof computer device (1) comprising a sealed enclosure (10), in turn comprising a hollow metal body (20) having an inside surface (22); a computer processor (30), arranged inside said enclosure (10); a tamper-detection sensor (40), which sensor (40) in turn comprises a tamper-detecting membrane (40) forming a sealed container in which the computer processor (30) is arranged, which membrane (40) is arranged on, and in direct thermal contact with, the said hollow metal body (20); and a metal heat sink structure (50) thermally connected to the computer processor (30), wherein the metal heat sink structure (50) is also arranged in direct thermal contact with a side of the membrane (40) not facing the said inside surface (22), so that the membrane (40) is sandwiched between the hollow metal body (20) and the metal heat sink structure (50) so that thermal connection is achieved between the metal heat sink structure (50) and the enclosure (10), via the membrane (40). The invention also relates to a method for manufacturing such a computer device.