From Langevin to Fokker-Plank equation

Question

I derived from the Langevin equation for the overdamped case of Brownian particle with mass m and charge q in 3D space with a constant homogeneous magnetic field $\vec{B}$ directed along z-axis and with 3-component Gaussian White noise the equation in the form $$\frac{d \vec{X} (t)}{dt}=C \vec{\Gamma} (t),$$ where $C$ is a 3x3 matrix with constant coefficients. Does this facts allow me to conclude that the corresponding Fokker-Planck equation is $$\frac{\partial{f}}{\partial{t}}=\frac{1}{2}\sum_{i=1}^3 \sum_{i=1}^3 C_{ij} \frac{\partial^{2}{f}}{\partial{x_{i}} \partial{x_{j}}},$$ where $C_{ij}$ are the elements (constants) of a matrix $C$? I think that all the coefficients $\alpha_{i}$ which are in the first partial derivative with respect to $x_{i}$ are zeros, but I am slightly in doubt. Could you, please, kindly confirm or disprove my conclusion?