diff --git a/itbit_api.py b/itbit_api.py
index 38a35e6..bb9ebdc 100644
--- a/itbit_api.py
+++ b/itbit_api.py
@@ -159,8 +159,8 @@ def make_request(self, verb, url, body_dict):
 
         auth_headers = {
             'Authorization': self.clientKey + ':' + signature.decode('utf8'),
-            'X-Auth-Timestamp': timestamp,
-            'X-Auth-Nonce': nonce,
+            'X-Auth-Timestamp': str(timestamp),
+            'X-Auth-Nonce': str(nonce),
             'Content-Type': 'application/json'
         }