A disc pump system includes a pump body having a substantially cylindrical shape defining a cavity for containing a fluid. The cavity having a resonant cavity frequency is formed by an internal sidewall and substantially closed at both ends by a first end wall and a driven end wall. The disc pump system includes an actuator that is driven a frequency (f) that corresponds to the fundamental resonant frequency of the actuator. The internal sidewall is configured to expand and contract in response to changes in temperature, thereby causing the actuator and cavity to have approximately the same resonant frequencies over a range of operating temperatures.