From ae6965a4e73cd5aad04e1c6831f48e7f0ecafc04 Mon Sep 17 00:00:00 2001
From: Timon Kruiper <timonkruiper@gmail.com>
Date: Wed, 1 Apr 2020 20:40:13 +0200
Subject: [PATCH] Fix undefined behavior when shift amount is 64

---
 src/bigint.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/bigint.cpp b/src/bigint.cpp
index 644e25837e..dd04363e82 100644
--- a/src/bigint.cpp
+++ b/src/bigint.cpp
@@ -1430,7 +1430,7 @@ void bigint_shr(BigInt *dest, const BigInt *op1, const BigInt *op2) {
         uint64_t digit = op1_digits[op_digit_index];
         size_t dest_digit_index = op_digit_index - digit_shift_count;
         digits[dest_digit_index] = carry | (digit >> leftover_shift_count);
-        carry = digit << (64 - leftover_shift_count);
+        carry = (leftover_shift_count != 0) ? (digit << (64 - leftover_shift_count)) : 0;
 
         if (dest_digit_index == 0) { break; }
         op_digit_index -= 1;