A dispensing device for dispensing a substance, preferably a medicament dispenser, more preferably an inhaler, yet more preferably a pressurised metered dose inhaler (pDMI), comprising:- a housing in which the substance is receivable and which has a dispensing nozzle from which the substance is in use dispensed; a dispensing member which is relatively movable in the housing to cause dispensing of the substance from the nozzle; and a closure for releasable mounting on the nozzle for closure thereof; wherein the closure comprises a cap member which is configured and arranged with respect to the nozzle such as to be capable of being slid over the nozzle in an intended orientation of the cap member; wherein in the intended orientation of the cap member the closure is securably mounted on the nozzle by sliding the cap member over the nozzle by a predetermined amount to a stationary position; wherein the closure further has a restricting member which, when the closure is securably mounted to the nozzle with the cap member in the intended orientation, restricts relative movement between the dispensing member and the housing such that dispensing of the substance is prevented; and wherein the restricting member extends through the nozzle when the closure is securably mounted to the nozzle with the cap member in the intended orientation; characterised in that: the cap member is configured and arranged with respect to the nozzle such as to be capable of being slid over the nozzle in an unintended orientation of the cap member; and the housing and the closure are configured and arranged with respect to each other such that the cap member cannot slide over the nozzle by the predetermined amount to a stationary position when in the unintended orientation thereby to indicate to the user that the closure is not correctly mounted on the nozzle. a housing in which the substance is receivable and which has a dispensing nozzle from which the substance is in use dispensed; a dispensing member which is relatively movable in the housing to cause dispensing of the substance from the nozzle; and a closure for releasable mounting on the nozzle for closure thereof; wherein the closure comprises a cap member which is configured and arranged with respect to the nozzle such as to be capable of being slid over the nozzle in an intended orientation of the cap member; wherein in the intended orientation of the cap member the closure is securably mounted on the nozzle by sliding the cap member over the nozzle by a predetermined amount to a stationary position; wherein the closure further has a restricting member which, when the closure is securably mounted to the nozzle with the cap member in the intended orientation, restricts relative movement between the dispensing member and the housing such that dispensing of the substance is prevented; and wherein the restricting member extends through the nozzle when the closure is securably mounted to the nozzle with the cap member in the intended orientation; characterised in that: the cap member is configured and arranged with respect to the nozzle such as to be capable of being slid over the nozzle in an unintended orientation of the cap member; and the housing and the closure are configured and arranged with respect to each other such that the cap member cannot slide over the nozzle by the predetermined amount to a stationary position when in the unintended orientation thereby to indicate to the user that the closure is not correctly mounted on the nozzle. the cap member is configured and arranged with respect to the nozzle such as to be capable of being slid over the nozzle in an unintended orientation of the cap member; and the housing and the closure are configured and arranged with respect to each other such that the cap member cannot slide over the nozzle by the predetermined amount to a stationary position when in the unintended orientation thereby to indicate to the user that the closure is not correctly mounted on the nozzle.