diff --git a/nbviewer/providers/__init__.py b/nbviewer/providers/__init__.py
index 19f05b77..9b1a7ea9 100644
--- a/nbviewer/providers/__init__.py
+++ b/nbviewer/providers/__init__.py
@@ -10,7 +10,8 @@
 ]
 
 default_rewrites = [
-    "nbviewer.providers.{}".format(prov) for prov in ["gist", "github", "dropbox", "url", "s3"]
+    "nbviewer.providers.{}".format(prov)
+    for prov in ["gist", "github", "dropbox", "url", "s3"]
 ]
 
 
@@ -86,7 +87,9 @@ def _load_provider_feature(feature, providers, **handler_names):
             continue
         else:
             # Ex: provider_handlers['url_handler'] = handler_names['url_handler']
-            provider_handlers[provider_handler_key] = handler_names[provider_handler_key]
+            provider_handlers[provider_handler_key] = handler_names[
+                provider_handler_key
+            ]
 
     features = []