<p>The module retainer (1) for accommodating a functional module comprises a clamp (20) for attaching the module retainer (1) to a supporting belt (2). The clamp (20) has a first side (21) that is pivotally attached to a main structure (10) of the module retainer (1). The module retainer (1) further comprises at least one snap-fit (12) for operably attaching a second side (22) of the clamp (20) to the main structure (10) and for fixing the clamp (20) in a closed position in which the supporting belt (2) is embraced. The snap-fit (12) is designed and positioned such that it gets obstructed by a functional module (3) inserted in the main structure (10) of the module retainer (1) and secures the clamp (20) in the closed position.</p>