diff --git a/src/frontend/numparam/mystring.c b/src/frontend/numparam/mystring.c
index 297b7a970..d699522f6 100644
--- a/src/frontend/numparam/mystring.c
+++ b/src/frontend/numparam/mystring.c
@@ -98,7 +98,7 @@ cadd(DSTRINGPTR dstr_p, char c)
 void
 scopyd(DSTRINGPTR dst, const DSTRINGPTR src)  /* returns success flag */
 {
-    (void) ds_clear(dst);
+    ds_clear(dst);
     if (ds_cat_ds(dst, src) != DS_E_OK) {
         controlled_exit(-1);
     }
@@ -127,6 +127,7 @@ pscopy(DSTRINGPTR dstr_p, const char *t, const char *stop)
         stop = strchr(t, '\0');
     }
 
+    ds_clear(dstr_p);
     if (ds_cat_mem(dstr_p, t, stop - t) != DS_E_OK) {
         controlled_exit(-1);
     }
diff --git a/src/frontend/numparam/numpaif.h b/src/frontend/numparam/numpaif.h
index 6a1d84f26..800f4c701 100644
--- a/src/frontend/numparam/numpaif.h
+++ b/src/frontend/numparam/numpaif.h
@@ -16,7 +16,7 @@ struct card;
 extern char  *nupa_copy(struct card *c);
 extern int    nupa_eval(struct card *card);
 extern void   nupa_signal(int sig);
-extern void   nupa_scan(struct card *card);
+extern void   nupa_scan(const struct card *card);
 extern void   nupa_list_params(FILE *cp_out);
 extern double nupa_get_param(char *param_name, int *found);
 extern void   nupa_add_param(char *param_name, double value);
diff --git a/src/frontend/numparam/numparam.h b/src/frontend/numparam/numparam.h
index d9258787d..e5076a4c2 100644
--- a/src/frontend/numparam/numparam.h
+++ b/src/frontend/numparam/numparam.h
@@ -58,7 +58,7 @@ typedef struct {                /* the input scanner data structure */
 void initdico(dico_t *);
 int donedico(dico_t *);
 void dico_free_entry(entry_t *);
-bool defsubckt(dico_t *, struct card *);
+bool defsubckt(dico_t *, const struct card *);
 int findsubckt(dico_t *, const char *s);
 bool nupa_substitute(dico_t *, const char *s, char *r);
 bool nupa_assignment(dico_t *, const char *s, char mode);
diff --git a/src/frontend/numparam/spicenum.c b/src/frontend/numparam/spicenum.c
index d4405964b..52255a050 100644
--- a/src/frontend/numparam/spicenum.c
+++ b/src/frontend/numparam/spicenum.c
@@ -246,8 +246,9 @@ transform(dico_t *dico, DSTRINGPTR dstr_p, bool incontrol)
             char *params;
             /* split off any "params" tail */
             params = strstr(s, "params:");
-            if (params)
-                pscopy(dstr_p, s, params);
+            if (params) {
+                ds_set_length(dstr_p, params - s);
+            }
             category = 'S';
         } else if (prefix(".control", s)) {
             category = 'C';
@@ -387,7 +388,7 @@ nupa_done(void)
 
 /* SJB - Scan the line for subcircuits */
 void
-nupa_scan(struct card *card)
+nupa_scan(const struct card *card)
 {
     defsubckt(dicoS, card);
 }
diff --git a/src/frontend/numparam/xpressn.c b/src/frontend/numparam/xpressn.c
index cdd5299d0..78fb231c9 100644
--- a/src/frontend/numparam/xpressn.c
+++ b/src/frontend/numparam/xpressn.c
@@ -494,7 +494,7 @@ nupa_define(dico_t *dico,
 
 
 bool
-defsubckt(dico_t *dico, struct card *card)
+defsubckt(dico_t *dico, const struct card *card)
 /* called on 1st pass of spice source code,
    to enter subcircuit names
 */
diff --git a/src/frontend/subckt.c b/src/frontend/subckt.c
index fcaa359b0..fcdcce9ee 100644
--- a/src/frontend/subckt.c
+++ b/src/frontend/subckt.c
@@ -239,13 +239,17 @@ inp_subcktexpand(struct card *deck) {
 
         nupa_signal(NUPADECKCOPY);
         /* get the subckt names from the deck */
-        for (c = deck; c; c = c->nextcard)    /* first Numparam pass */
-            if (ciprefix(".subckt", c->line))
+        for (c = deck; c; c = c->nextcard) {    /* first Numparam pass */
+            if (ciprefix(".subckt", c->line)) {
                 nupa_scan(c);
+            }
+        }
+
         /* now copy instances */
         for (c = deck; c; c = c->nextcard) {  /* first Numparam pass */
-            if (*(c->line) == '*')
+            if (*(c->line) == '*') {
                 continue;
+            }
             c->line = nupa_copy(c);
         }
 
@@ -456,7 +460,6 @@ doit(struct card *deck, wordlist *modnames) {
         struct card *prev_of_c = NULL;
 
         while (c) {
-
             if (ciprefix(sbend, c->line)) {  /* if line == .ends  */
                 fprintf(cp_err, "Error: misplaced %s line: %s\n", sbend,
                         c->line);