Resistive open faults (ROFs) represent common manufacturing defects in IC interconnects and result in delay faults that cause timing failures and reliability risks. The nonmonotonic dependence of ROF-induced delay faults on the supply voltage (VDD) poses a concern as to whether single-VDD testing will suffice for low power nanometric designs. Our analysis shows multi-VDD tests could be required, depending on the test speed. This knowledge can be exploited in small delay fault testing to reduce the chances of test escapes while minimizing cost. © 1993-2012 IEEE.