An injection device for the delivery of medicament, the device comprising: a housing; an extendable plunger comprising a leading portion and a trailing portion configured to allow the plunger to extend from an initial length to a maximum extended length, the trailing portion being arranged to move in the forward direction in response to the extendable plunger reaching its maximum extension, the plunger portions being slidably mounted within the housing; an actuation mechanism configured to move the leading portion of the plunger forwardly relative to a syringe so as to express medicament from the syringe; a trigger arrangement moveable in use relative to the housing as part of an activation movement to release the actuation mechanism; and an indicator for providing an end of dose indication, wherein the indicator is responsive to the forward movement of the trailing portion of the plunger and configured to provide an audible and/or tactile and/or visual indication of the end of dose when the plunger reaches or approaches its forwardmost position; wherein the indicator is biased towards the indicating position and the trailing portion of the plunger is arranged to hold the indicator against said bias; the device being characterised in that: the indicator comprises an aperture including a radially inwardly extending portion around at least a portion of the aperture, the trailing portion comprises a recess defined by a portion of reduced diameter to receive the radially inwardly extending portion proximal to its rearward end; and the indicator is configured to move forward relative to at least the trailing portion of the plunger in response to the activation movement of the trigger arrangement to increase the mechanical coupling between the indicator and the trailing portion of the plunger holding the indicator in a stressed position. a housing; an extendable plunger comprising a leading portion and a trailing portion configured to allow the plunger to extend from an initial length to a maximum extended length, the trailing portion being arranged to move in the forward direction in response to the extendable plunger reaching its maximum extension, the plunger portions being slidably mounted within the housing; an actuation mechanism configured to move the leading portion of the plunger forwardly relative to a syringe so as to express medicament from the syringe; a trigger arrangement moveable in use relative to the housing as part of an activation movement to release the actuation mechanism; and an indicator for providing an end of dose indication, wherein the indicator is responsive to the forward movement of the trailing portion of the plunger and configured to provide an audible and/or tactile and/or visual indication of the end of dose when the plunger reaches or approaches its forwardmost position; wherein the indicator is biased towards the indicating position and the trailing portion of the plunger is arranged to hold the indicator against said bias; the device being characterised in that: the indicator comprises an aperture including a radially inwardly extending portion around at least a portion of the aperture, the trailing portion comprises a recess defined by a portion of reduced diameter to receive the radially inwardly extending portion proximal to its rearward end; and the indicator is configured to move forward relative to at least the trailing portion of the plunger in response to the activation movement of the trigger arrangement to increase the mechanical coupling between the indicator and the trailing portion of the plunger holding the indicator in a stressed position. the indicator comprises an aperture including a radially inwardly extending portion around at least a portion of the aperture, the trailing portion comprises a recess defined by a portion of reduced diameter to receive the radially inwardly extending portion proximal to its rearward end; and the indicator is configured to move forward relative to at least the trailing portion of the plunger in response to the activation movement of the trigger arrangement to increase the mechanical coupling between the indicator and the trailing portion of the plunger holding the indicator in a stressed position.