A tracheostomy valve configured to be in fluid communication with a patient's trachea, the valve comprising a hollow valve body, a flexible membrane adapted to work as a check valve opening the valve when the patient inhales and sealingly closing the valve when the patient exhales, and a cap with at least one through hole making the cap fenestrated, the hollow valve body having a through hole forming a passageway for fluid extending between an inner end being an outlet of the hollow valve body and an outer end being an inlet of the hollow valve body, wherein the fenestrated cap is configured to be detachably attached to the outer valve body end, and the inner valve body end is configured to be in fluid communication with the patient's trachea, the fenestrated cap comprising an inner end facing towards and adapted to sealingly fit into or onto the outer valve body end when detachably attached thereto and an outer end facing in the opposite direction of the inner cap end, the inner cap end having an opening defined by a circumferential rim with a size largely corresponding to the inner size of the outer valve body end, wherein the fenestrated cap comprises a centre hub between which and the circumferential rim the at least one through hole is arranged forming at least one spoke (13a-f) extending between the centre hub and the circumferential rim, wherein the at least one spoke (13a-f) of the fenestrated cap has an inner surface facing towards the circumferential rim and the inner cap end, which inner spoke surface is curved in only one plane of extension in a direction towards the outer cap end, characterized in that the fenestrated cap and the flexible membrane are configured to be detachably connected together to form a membrane and cap unit being adapted to sealingly fit into or onto the outer valve body end when detachably attached thereto, that the membrane and cap unit comprises a detachable fastener configured to securely clamp the flexible membrane in fluid sealing abutment with the inner spoke surface of the fenestrated cap when the patient is not inhaling or exhales, wherein the centre hub of the fenestrated cap comprises a protrusion with a circular cross-section arranged centrally and extending from the centre hub towards the inner cap end into a free end, that the detachable fastener is configured to be slid over the centre protrusion of the cap when assembling the cap and the flexible membrane together such that the flexible membrane is sealingly seated between the detachable fastener and the inner spoke surface by being pushed by the detachable fastener towards the inner spoke surface such that the membrane is formed or bends into a corresponding curved shape sealingly fitting to the curved shape of the inner spoke surface when the patient is not inhaling or exhales. that the fenestrated cap and the flexible membrane are configured to be detachably connected together to form a membrane and cap unit being adapted to sealingly fit into or onto the outer valve body end when detachably attached thereto, that the membrane and cap unit comprises a detachable fastener configured to securely clamp the flexible membrane in fluid sealing abutment with the inner spoke surface of the fenestrated cap when the patient is not inhaling or exhales, wherein the centre hub of the fenestrated cap comprises a protrusion with a circular cross-section arranged centrally and extending from the centre hub towards the inner cap end into a free end, that the detachable fastener is configured to be slid over the centre protrusion of the cap when assembling the cap and the flexible membrane together such that the flexible membrane is sealingly seated between the detachable fastener and the inner spoke surface by being pushed by the detachable fastener towards the inner spoke surface such that the membrane is formed or bends into a corresponding curved shape sealingly fitting to the curved shape of the inner spoke surface when the patient is not inhaling or exhales.