diff --git a/bitutilities.py b/bitutilities.py
index e8179fe..30a16aa 100644
--- a/bitutilities.py
+++ b/bitutilities.py
@@ -100,6 +100,7 @@ def binary_sum(first_term: BasicRegister, second_term: BasicRegister, return_rem
         c.memory[i] = bool(current_bit_sum & 1)
 
     final_bit_sum = a.memory[0] + b.memory[0] + carry
+    carry = bool(final_bit_sum & 2)
     c.memory[0] = bool(final_bit_sum & 1)
 
     if return_remainder: