Gas fixing tool, including at least one combustion chamber, a trigger, a device for injecting fuel into the at least one chamber, a member for actuating the device, and a bearing member intended to be brought to bear on a support material, characterized in that it further comprises a safety member configured to cooperate on the one hand with the actuating member and on the other hand with the trigger, so that the trigger is locked in its first position when the actuating member is in a first position.