Research on fault detection for high-voltage direct current (HVDC) grids has had a focus on single-ended DC fault detection using information from only the local line end. This paper proposes the use of additional information from neighbouring lines around the same busbar in a multiple-input single-output (MISO) fault detection. Simulations results show that the protection’s dependability and security margins are increased which is particularly useful for remote faults in long lines with small line inductors. A discussion on practical implementation taking into account possible intellectual property (IP) aspects is added. A MISO fault detection can be useful to overcome some of the uncertainties due to missing knowledge about implementation details.