diff --git a/src/include/ngspice/fteinp.h b/src/include/ngspice/fteinp.h
index 8d449c7ad..4f8e6623e 100644
--- a/src/include/ngspice/fteinp.h
+++ b/src/include/ngspice/fteinp.h
@@ -21,6 +21,7 @@ struct line {
     char *li_error;
     struct line *li_next;
     struct line *li_actual;
+    unsigned short level[NESTINGDEPTH];
 } ;
 
 /* Listing types. */
diff --git a/src/include/ngspice/inpdefs.h b/src/include/ngspice/inpdefs.h
index b4623f77b..cf575c2d3 100644
--- a/src/include/ngspice/inpdefs.h
+++ b/src/include/ngspice/inpdefs.h
@@ -17,6 +17,7 @@ typedef struct INPtables INPtables;
 typedef struct card card;
 typedef struct INPmodel INPmodel;
 
+#define NESTINGDEPTH 10
 
 struct INPtab {
     char *t_ent;
@@ -68,6 +69,7 @@ struct card{
     char *error;
     card *nextcard;
     card *actualLine;
+    unsigned short level[NESTINGDEPTH];
 };
 
 /* structure used to save models in after they are read during pass 1 */