An electrical measuring instrument, in particular an air flow rate meter in an internal combustion engine, which is exposed to a flowing medium, has a mount, a substrate retained in the mount, terminals, and a temperature-dependent measuring resistor disposed on the substrate between two of the terminals. The substrate has a side at which the medium strikes the measuring resistor. A device for drift reduction in the electrical measuring instrument includes an obstruction disposed upstream of the substrate at the side at which the medium strikes the measuring resistor. The obstruction interrupts a dirt film developing between the terminals.