A method for detection of a fluid leak related to at least one piston machine (1), where the method includes: —attaching a pressure sensor (18, 24) to at least a pressure side of the at least one piston machine (1); —measuring the pressure on the pressure side of the at least one piston machine (1); —attaching a transmitter (28) to the at least one piston machine (1), said transmitter (28) rendering a signal for calculating the rotational speed of the at least one piston machine (1); —calculating the speed of the at least one piston machine (1); —calculating the sum of nominal flow rates from all piston machines (1); —calculating a flow rate compensation factor; —calculating a normalized pressure (42) to be equal to the discharge pressure multiplied by the said compensation factor for the flow rate; and —monitoring the normalized pressure (42) to detect a leakage.