diff --git a/src/frontend/options.c b/src/frontend/options.c
index 8796cee4c..9969bbb7f 100644
--- a/src/frontend/options.c
+++ b/src/frontend/options.c
@@ -34,6 +34,9 @@ bool ft_ngdebug = FALSE, ft_stricterror = FALSE;
  * plot and circuit environment variables.
  */
 
+/* this is broken, returns sometimes "new" struct variable
+ * and sometimes already/still "used" struct variable (owned by someone else)
+ */
 struct variable *
 cp_enqvar(char *word)
 {
@@ -73,8 +76,9 @@ cp_enqvar(char *word)
     if (plot_cur) {
         for (vv = plot_cur->pl_env; vv; vv = vv->va_next)
             if (eq(vv->va_name, word))
-                return (vv);
+                return (vv);    /* <= return an already used struct variable */
         if (eq(word, "curplotname"))
+            /* return a new allocaed struct variable */
             return var_alloc_string(copy(word), copy(plot_cur->pl_name), NULL);
         if (eq(word, "curplottitle"))
             return var_alloc_string(copy(word), copy(plot_cur->pl_title), NULL);
diff --git a/src/frontend/variable.c b/src/frontend/variable.c
index bbc3f178c..2a87032d8 100644
--- a/src/frontend/variable.c
+++ b/src/frontend/variable.c
@@ -758,7 +758,7 @@ vareval(char *string)
             vfree = v = cp_enqvar(string);
         wl = wl_cons(copy(v ? "1" : "0"), NULL);
         tfree(oldstring);
-        free_struct_variable(vfree);
+        free_struct_variable(vfree); /* bug: free still used struct variable */
         return (wl);
 
     case '#':
@@ -780,7 +780,7 @@ vareval(char *string)
             i = (v->va_type != CP_BOOL);
         wl = wl_cons(tprintf("%d", i), NULL);
         tfree(oldstring);
-        free_struct_variable(vfree);
+        free_struct_variable(vfree); /* bug: free still used struct variable */
         return (wl);
 
     case '\0':
@@ -818,7 +818,7 @@ vareval(char *string)
         return (NULL);
     }
     wl = cp_varwl(v);
-    free_struct_variable(vfree);
+    free_struct_variable(vfree); /* bug: free still used struct variable */
 
     /* Now parse and deal with 'range' ... */
     if (range) {