diff --git a/src/frontend/numparam/xpressn.c b/src/frontend/numparam/xpressn.c
index 0b15e5081..652dceb0b 100644
--- a/src/frontend/numparam/xpressn.c
+++ b/src/frontend/numparam/xpressn.c
@@ -547,7 +547,7 @@ findsubckt(dico_t *dico, const char * const s)
 /* input: s is a subcircuit invocation line.
    returns 0 if not found, else the stored definition line number value */
 {
-    const char *k_ptr;
+    const char *k_ptr = s + strlen(s);
 
     entry_t *entry;             /* symbol table entry */
     SPICE_DSTRING ustr;         /* u= subckt name is last token in string s */
@@ -556,15 +556,13 @@ findsubckt(dico_t *dico, const char * const s)
 
     spice_dstring_init(&ustr);
 
-    (k_ptr - s) = (int) strlen(s);
-
     while (((k_ptr - s) >= 0) && (s[(k_ptr - s)] <= ' '))
-        (k_ptr - s)--;
+        k_ptr--;
 
     j = (int) (k_ptr - s);
 
     while (((k_ptr - s) >= 0) && (s[(k_ptr - s)] > ' '))
-        (k_ptr - s)--;
+        k_ptr--;
 
     pscopy_up(&ustr, s, (int) (k_ptr - s) + 1, j - (int) (k_ptr - s));
     entry = entrynb(dico, spice_dstring_value(&ustr));