diff --git a/src/frontend/inp.c b/src/frontend/inp.c
index 3b7aaf432..1284b8570 100644
--- a/src/frontend/inp.c
+++ b/src/frontend/inp.c
@@ -295,6 +295,23 @@ line_free_x(struct line *deck, bool recurse)
     }
 }
 
+
+/* concatenate two lists, destructively altering the first one */
+struct line *
+line_nconc(struct line *head, struct line *rest)
+{
+    struct line *p = head;
+    if (!rest)
+        return head;
+    if (!head)
+        return rest;
+    while (p->li_next)
+        p = p->li_next;
+    p->li_next = rest;
+    return head;
+}
+
+
 /* reverse the linked list struct line */
 struct line *
 line_reverse(struct line *head)
diff --git a/src/include/ngspice/fteext.h b/src/include/ngspice/fteext.h
index a44c6b1e0..0d271192e 100644
--- a/src/include/ngspice/fteext.h
+++ b/src/include/ngspice/fteext.h
@@ -214,6 +214,8 @@ extern void inp_list(FILE *file, struct line *deck, struct line *extras, int typ
 extern struct line *inp_readall(FILE *fp, char *dir_name, bool comfile, bool intfile);
 extern FILE *inp_pathopen(char *name, char *mode);
 extern char *search_identifier(char *str, const char *identifier, char *str_begin);
+extern struct line *line_nconc(struct line *head, struct line *rest);
+extern struct line *line_reverse(struct line *head);
 extern void mc_free(void);
 void eval_seed_opt(struct line *deck);