Vaporization devices and methods of operating them are described. In particular, apparatuses with a resistive heating element, electrical circuitry for measuring a voltage between the resistive heating element and a reference resistor, and a microcontroller for controlling a temperature of the resistive heating element in response to a determined resistance are described. The electrical circuitry may comprise the reference resistor, a first switch operable to interrupt the flow of current from the power source through the resistive heating element, a second switch operable to add the reference resistor in series with the resistive heating element when the flow of current from the power source through the resistive heating element is interrupted by operation of the first switch, and a voltage divider configured to measure a voltage between the resistive heating element and the reference resistor.