diff --git a/sift/client.py b/sift/client.py
index cef3d57..5b34e2e 100644
--- a/sift/client.py
+++ b/sift/client.py
@@ -2,6 +2,7 @@
 See: https://siftscience.com/docs/references/events-api
 """
 
+import decimal
 import json
 import requests
 import requests.auth
@@ -26,6 +27,11 @@ def _quote_path(s):
     # optional arg to override this
     return urllib.parse.quote(s, '')
 
+class DecimalEncoder(json.JSONEncoder):
+    def default(self, o):
+        if isinstance(o, decimal.Decimal):
+            return (str(o),)
+        return super(DecimalEncoder, self).default(o)
 
 class Client(object):
 
@@ -165,7 +171,7 @@ def track(
         try:
             response = self.session.post(
                 path,
-                data=json.dumps(properties),
+                data=json.dumps(properties, cls=DecimalEncoder),
                 headers=headers,
                 timeout=timeout,
                 params=params)
diff --git a/tests/test_client.py b/tests/test_client.py
index bb32ce3..9252d76 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -3,6 +3,7 @@
 import sys
 import unittest
 import warnings
+from decimal import Decimal
 
 import mock
 import requests.exceptions
@@ -19,7 +20,7 @@ def valid_transaction_properties():
     return {
         '$buyer_user_id': '123456',
         '$seller_user_id': '654321',
-        '$amount': 1253200,
+        '$amount': Decimal('1253200.0'),
         '$currency_code': 'USD',
         '$time': int(datetime.datetime.now().strftime('%s')),
         '$transaction_id': 'my_transaction_id',
diff --git a/tests/test_client_v203.py b/tests/test_client_v203.py
index 0da8f11..a7af5b8 100644
--- a/tests/test_client_v203.py
+++ b/tests/test_client_v203.py
@@ -1,4 +1,5 @@
 import datetime
+from decimal import Decimal
 import warnings
 import json
 import mock
@@ -16,7 +17,7 @@ def valid_transaction_properties():
     return {
         '$buyer_user_id': '123456',
         '$seller_user_id': '654321',
-        '$amount': 1253200,
+        '$amount': Decimal('1253200.0'),
         '$currency_code': 'USD',
         '$time': int(datetime.datetime.now().strftime('%s')),
         '$transaction_id': 'my_transaction_id',