diff --git a/src/frontend/cpitf.c b/src/frontend/cpitf.c
index 21c777815..28fe87906 100644
--- a/src/frontend/cpitf.c
+++ b/src/frontend/cpitf.c
@@ -299,9 +299,9 @@ ft_cpinit(void)
 bool
 cp_istrue(wordlist *wl)
 {
-    int i;
     struct dvec *v;
     struct pnode *names;
+    bool rv;
 
     /* First do all the csh-type stuff here... */
     wl = wl_copy(wl);
@@ -314,24 +314,9 @@ cp_istrue(wordlist *wl)
 
     v = ft_evaluate(names);
 
-    for (; v; v = v->v_link2)
-        if (isreal(v)) {
-            for (i = 0; i < v->v_length; i++)
-                if (v->v_realdata[i] != 0.0) {
-                    free_pnode(names);
-                    return (TRUE);
-                }
-        } else {
-            for (i = 0; i < v->v_length; i++)
-                if ((realpart(v->v_compdata[i]) != 0.0) ||
-                    (imagpart(v->v_compdata[i]) != 0.0)) {
-                    free_pnode(names);
-                    return (TRUE);
-                }
-        }
-
+    rv = !vec_iszero(v);
     free_pnode(names);
-    return (FALSE);
+    return rv;
 }
 
 
diff --git a/src/frontend/vectors.c b/src/frontend/vectors.c
index 78fb97a4b..70c02ef46 100644
--- a/src/frontend/vectors.c
+++ b/src/frontend/vectors.c
@@ -883,6 +883,33 @@ vec_free_x(struct dvec *v)
 }
 
 
+/*
+ * return TRUE if every vector element is zero
+ */
+
+bool
+vec_iszero(struct dvec *v)
+{
+    int i;
+
+    for (; v; v = v->v_link2)
+        if (isreal(v))
+            for (i = 0; i < v->v_length; i++) {
+                if (v->v_realdata[i] != 0.0)
+                    return FALSE;
+            }
+        else
+            for (i = 0; i < v->v_length; i++) {
+                if (realpart(v->v_compdata[i]) != 0.0)
+                    return FALSE;
+                if (imagpart(v->v_compdata[i]) != 0.0)
+                    return FALSE;
+            }
+
+    return TRUE;
+}
+
+
 /* This is something we do in a few places...  Since vectors get copied a lot,
  * we can't just compare pointers to tell if two vectors are 'really' the same.
  */
diff --git a/src/include/ngspice/fteext.h b/src/include/ngspice/fteext.h
index 85fc2bd18..059554c48 100644
--- a/src/include/ngspice/fteext.h
+++ b/src/include/ngspice/fteext.h
@@ -323,6 +323,7 @@ extern int ft_typnum(char *);
 
 /* vectors.c */
 
+extern bool vec_iszero(struct dvec *v);
 extern bool vec_eq(struct dvec *v1, struct dvec *v2);
 extern int plot_num;
 extern struct dvec *vec_fromplot(char *word, struct plot *plot);