A new procedure to determine the noise parameters of a linear two-port from a set of experimental data is introduced. It consists in directly solving a system of four nonlinear equations instead of using a least-squares fit or casting the original equations in a form that is linear with respect to the four noise parameters. The proposed symbolic solution provides insight in error analysis. This method is compared with Minimax optimisation performed on an experimental set of noise figures measured for nine different source admittances.