An electrically heated aerosol-generating device for use with a consumable cartridge comprising a storage portion containing an aerosol-forming substrate, the storage portion having a fluid permeable internal surface surrounding an open ended passage extending through the cartridge, the device comprising: a main housing having a cavity for receiving a consumable cartridge; a closure body engageable with the main housing to enclose the cartridge in the cavity; and a heater assembly for heating the cartridge, the heater assembly comprising: an elongate piercing assembly arranged to extend into the open-ended passage of the cartridge and defining an internal airflow passage forming part of an airflow pathway through the device; and one or more electric heaters (400, 401, 403, 405) fixed to the elongate piercing assembly, the one or more electric heaters each having at least one heating element for heating the aerosol forming substrate when the cartridge is enclosed in the cavity, wherein the elongate piercing assembly comprises a first hollow shaft portion connected to the main housing and having a first piercing surface at its distal end for breaking through a first frangible seal across a first end of the open ended passage when the cartridge is inserted into the cavity, and a second hollow shaft portion connected to the closure body and having a second piercing surface at its distal end for breaking through a second frangible seal across a second end of the open ended passage when the closure body is engaged with the main housing, wherein the first and second hollow shaft portions are arranged to extend along the same longitudinal axis when the closure body is engaged with the main housing, and wherein the first and second hollow shaft portions are sized to meet at a junction such that the elongate piercing assembly extends along the entire length of the cavity when the closure body is engaged with the main housing. a main housing having a cavity for receiving a consumable cartridge; a closure body engageable with the main housing to enclose the cartridge in the cavity; and a heater assembly for heating the cartridge, the heater assembly comprising: an elongate piercing assembly arranged to extend into the open-ended passage of the cartridge and defining an internal airflow passage forming part of an airflow pathway through the device; and one or more electric heaters (400, 401, 403, 405) fixed to the elongate piercing assembly, the one or more electric heaters each having at least one heating element for heating the aerosol forming substrate when the cartridge is enclosed in the cavity, wherein the elongate piercing assembly comprises a first hollow shaft portion connected to the main housing and having a first piercing surface at its distal end for breaking through a first frangible seal across a first end of the open ended passage when the cartridge is inserted into the cavity, and a second hollow shaft portion connected to the closure body and having a second piercing surface at its distal end for breaking through a second frangible seal across a second end of the open ended passage when the closure body is engaged with the main housing, wherein the first and second hollow shaft portions are arranged to extend along the same longitudinal axis when the closure body is engaged with the main housing, and wherein the first and second hollow shaft portions are sized to meet at a junction such that the elongate piercing assembly extends along the entire length of the cavity when the closure body is engaged with the main housing. an elongate piercing assembly arranged to extend into the open-ended passage of the cartridge and defining an internal airflow passage forming part of an airflow pathway through the device; and one or more electric heaters (400, 401, 403, 405) fixed to the elongate piercing assembly, the one or more electric heaters each having at least one heating element for heating the aerosol forming substrate when the cartridge is enclosed in the cavity, wherein the elongate piercing assembly comprises a first hollow shaft portion connected to the main housing and having a first piercing surface at its distal end for breaking through a first frangible seal across a first end of the open ended passage when the cartridge is inserted into the cavity, and a second hollow shaft portion connected to the closure body and having a second piercing surface at its distal end for breaking through a second frangible seal across a second end of the open ended passage when the closure body is engaged with the main housing, wherein the first and second hollow shaft portions are arranged to extend along the same longitudinal axis when the closure body is engaged with the main housing, and wherein the first and second hollow shaft portions are sized to meet at a junction such that the elongate piercing assembly extends along the entire length of the cavity when the closure body is engaged with the main housing.