Technologies are generally described to detect malware on field programmable gate arrays (FPGAs). In some examples, a power map of an FPGA executing coprocessors may be created by determining voltages associated with distinct areas within the FPGA. The power map may then be compared with expected activity information associated with the executing coprocessors to determine whether any mismatches occur, such as detected power usage where no power usage is expected. Mismatches may indicate the presence of malware executing on the FPGA.