diff --git a/mailchimp_transactional/api_client.py b/mailchimp_transactional/api_client.py
index c319fac..4f838b4 100644
--- a/mailchimp_transactional/api_client.py
+++ b/mailchimp_transactional/api_client.py
@@ -15,11 +15,13 @@
 import requests
 import json
 
+
 class ApiClientError(Exception):
     def __init__(self, text, status_code):
         self.text = text
         self.status_code = status_code
 
+
 class ApiClient(object):
     def __init__(self):
         self.host = "https://mandrillapp.com/api/1.0"
@@ -61,19 +63,24 @@ def call_api(self, resource_path, method, header_params=None, body=None, **kwarg
         # perform request and return response
         res = self.request(method, url, body, headers)
 
+        try:
+            res.raise_for_status()
+        except requests.exceptions.HTTPError:
+            raise ApiClientError(text=res.text, status_code=res.status_code)
+
         try:
             if 'application/json' in res.headers.get('content-type'):
                 data = res.json()
             else:
                 data = res.text
-        except Exception as err:
+        except Exception:
             data = None
 
         if data:
             if (res.ok):
                 return data
             else:
-                raise ApiClientError(text = data, status_code = res.status_code)
+                raise ApiClientError(text=data, status_code=res.status_code)
         else:
             return res
 
@@ -86,4 +93,4 @@ def request(self, method, url, body=None, headers=None, timeout=None):
         else:
             raise ValueError(
                 "http method must be `POST`"
-            )
\ No newline at end of file
+            )