diff --git a/acc/mhd_solver/stencil_defines.h b/acc/mhd_solver/stencil_defines.h
index dbd632e..ebec464 100644
--- a/acc/mhd_solver/stencil_defines.h
+++ b/acc/mhd_solver/stencil_defines.h
@@ -123,6 +123,7 @@
         /* Additional helper params */\
         /* (deduced from other params do not set these directly!) */\
         FUNC(AC_G_const),\
+        FUNC(AC_unit_mass),\
         FUNC(AC_GM_star),\
         FUNC(AC_sq2GM_star),\
         FUNC(AC_cs2_sound), \
diff --git a/src/standalone/config_loader.cc b/src/standalone/config_loader.cc
index e7885a3..0d6085b 100644
--- a/src/standalone/config_loader.cc
+++ b/src/standalone/config_loader.cc
@@ -137,11 +137,19 @@ update_config(AcMeshInfo* config)
         6.674e-8);                   // g/cm3/s GGS definition //TODO define in a separate module
     AcReal M_sun = AcReal(1.989e33); // g solar mass
 
-    config->real_params[AC_M_sink] = config->real_params[AC_M_sink_Msun] * M_sun /
-                                   ((config->real_params[AC_unit_length] *
-                                     config->real_params[AC_unit_length] *
-                                     config->real_params[AC_unit_length]) *
-                                     config->real_params[AC_unit_density]);
+
+    config->real_params[AC_unit_mass] = (config->real_params[AC_unit_length] *
+                                         config->real_params[AC_unit_length] *
+                                         config->real_params[AC_unit_length]) *
+                                         config->real_params[AC_unit_density];
+
+
+
+
+
+
+    config->real_params[AC_M_sink] = config->real_params[AC_M_sink_Msun] * M_sun / 
+	                             config->real_params[AC_unit_mass];
 
     config->real_params[AC_G_const] = G_CONST_CGS / ((config->real_params[AC_unit_velocity] *
                                                       config->real_params[AC_unit_velocity]) /