--- a/buffer.c	Mon Nov 21 19:52:28 2011 +0800
+++ b/buffer.c	Tue Nov 22 19:28:58 2011 +0700
@@ -288,12 +288,12 @@
 
 	dropbear_assert(fp != NULL);
 
-	if (SIGN(fp) == FP_NEG) {
+	if (fp->sign == FP_NEG) {
 		dropbear_exit("negative bignum");
 	}
 
 	/* zero check */
-	if (USED(fp) == 1 && DIGIT(fp, 0) == 0) {
+	if (fp_iszero(fp) == FP_YES) {
 		len = 0;
 	} else {
 		/* SSH spec requires padding for fpints with the MSB set, this code