We provide a proof of the first correction to the leading asymptotics of the ground-state energy of molecules with pseudo-relativistic electrons in the presence of a magnetic field. This is known as the ``relativistic Scott correction.'' It is shown that neither the leading term nor the Scott correction depends on the magnetic field. Our result extends a previous theorem by Erdös, Fournais, and Solovej to the critical case $\max_k Z_k\alpha = 2/\pi$, where $\alpha$ is the fine structure constant. Therefore, the full range $0 \leq \max_k Z_k\alpha \leq 2/\pi$ is now covered. ($\max_k Z_k\alpha = 0$ corresponds to $\alpha = 0$, which is the non-relativistic case.) Joint work with S. Fournais.