diff --git a/blockchain.py b/blockchain.py
index 4e92d07..d3b6d34 100644
--- a/blockchain.py
+++ b/blockchain.py
@@ -104,7 +104,7 @@ class Blockchain:
             'timestamp': time(),
             'transactions': self.current_transactions,
             'proof': proof,
-            'previous_hash': previous_hash or self.hash(self.chain[-1]),
+            'previous_hash': previous_hash or self.hash(last_block),
         }
 
         # Reset the current list of transactions