From 99f0728f236680a63e8ed30ec52dca5bbdfd705d Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Mon, 24 Nov 2014 21:29:25 +0100
Subject: [PATCH] Fix secp256k1_num_set_bin handling of 0

---
 src/num_gmp_impl.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/num_gmp_impl.h b/src/num_gmp_impl.h
index e45a59e0cdc..e7eae867635 100644
--- a/src/num_gmp_impl.h
+++ b/src/num_gmp_impl.h
@@ -71,6 +71,10 @@ static void secp256k1_num_set_bin(secp256k1_num_t *r, const unsigned char *a, un
     VERIFY_CHECK(alen > 0);
     VERIFY_CHECK(alen <= 64);
     int len = mpn_set_str(r->data, a, alen, 256);
+    if (len == 0) {
+        r->data[0] = 0;
+        len = 1;
+    }
     VERIFY_CHECK(len <= NUM_LIMBS*2);
     r->limbs = len;
     r->neg = 0;