An air mass flowmeter having a sensor module fitted in a tube for measuring a gas quantity flowing in the tube at a flow speed. The sensor module extends in the tube. A start of the sensor module defines a first plane and an end of the sensor module defines a second plane both normal to the direction of flow. Extended flow directing elements are arranged in the tube parallel to the direction of flow so that the gas flows onto end faces and wall regions of the flow elements. The wall regions extend between the first and second planes and increase the flow speed of the gas given a low flow speed, relative to the flow speed in the tube, and increase the flow speed of the gas to a lesser extent, given a high flow speed of the gas relative to the flow speed.