diff --git a/bigchaindb/common/transaction.py b/bigchaindb/common/transaction.py
index 23b8f169..00126cd9 100644
--- a/bigchaindb/common/transaction.py
+++ b/bigchaindb/common/transaction.py
@@ -264,7 +264,7 @@ class Output(object):
         output = {
             'public_keys': self.public_keys,
             'condition': condition,
-            'amount': self.amount
+            'amount': str(self.amount),
         }
         return output
 
@@ -381,7 +381,11 @@ class Output(object):
         except KeyError:
             # NOTE: Hashlock condition case
             fulfillment = data['condition']['uri']
-        return cls(fulfillment, data['public_keys'], data['amount'])
+        try:
+            amount = int(data['amount'])
+        except ValueError:
+            raise AmountError('Invalid amount: %s' % amount)
+        return cls(fulfillment, data['public_keys'], amount)
 
 
 class Transaction(object):
diff --git a/tests/common/test_transaction.py b/tests/common/test_transaction.py
index ec288de5..5a9ad766 100644
--- a/tests/common/test_transaction.py
+++ b/tests/common/test_transaction.py
@@ -83,7 +83,7 @@ def test_output_serialization(user_Ed25519, user_pub):
             'details': user_Ed25519.to_dict(),
         },
         'public_keys': [user_pub],
-        'amount': 1,
+        'amount': '1',
     }
 
     cond = Output(user_Ed25519, [user_pub], 1)
@@ -101,7 +101,7 @@ def test_output_deserialization(user_Ed25519, user_pub):
             'details': user_Ed25519.to_dict()
         },
         'public_keys': [user_pub],
-        'amount': 1,
+        'amount': '1',
     }
     cond = Output.from_dict(cond)
 
@@ -120,7 +120,7 @@ def test_output_hashlock_serialization():
             'uri': hashlock,
         },
         'public_keys': None,
-        'amount': 1,
+        'amount': '1',
     }
     cond = Output(hashlock, amount=1)
 
@@ -140,7 +140,7 @@ def test_output_hashlock_deserialization():
             'uri': hashlock
         },
         'public_keys': None,
-        'amount': 1,
+        'amount': '1',
     }
     cond = Output.from_dict(cond)