diff --git a/acc/mhd_solver/stencil_kernel.ac b/acc/mhd_solver/stencil_kernel.ac
index e0efa94..db83a3f 100644
--- a/acc/mhd_solver/stencil_kernel.ac
+++ b/acc/mhd_solver/stencil_kernel.ac
@@ -39,6 +39,7 @@ uniform Scalar AC_zorig;
 uniform Scalar AC_unit_density;
 uniform Scalar AC_unit_velocity;
 uniform Scalar AC_unit_length;
+uniform Scalar AC_unit_magnetic;
 // properties of gravitating star
 uniform Scalar AC_star_pos_x;
 uniform Scalar AC_star_pos_y;