@@ -16,9 +16,9 @@ void s_fp_add(fp_int *a, fp_int *b, fp_int *c)

   register fp_word  t;

   y       = MAX(a->used, b->used);

-  oldused = c->used;

+  oldused = MAX(c->used, FP_SIZE);

   c->used = y;

- 

+

   t = 0;

   for (x = 0; x < y; x++) {

       t         += ((fp_word)a->dp[x]) + ((fp_word)b->dp[x]);