Prevent code generation for including observable states in main.c

When using Simulink code generation to generate a reusable function for an embedded target, code generation always adds the following line in the ert_main.c:

static DW_$MODELNAME$ $MODELNAME$_DW;  /* Observable states */

which later on in main() is used once:

/* Pack model data into RTM */
$MODELNAME$_M->dwork = &$MODELNAME$_DW;

I would very much prefer if this symbol would not exist in the ert_main so I would like to ask where it comes from and how to perhaps control its placement?