diff --git a/.gitignore b/.gitignore
index 0ce72b41e..f40514dc8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,6 +9,7 @@ MANIFEST
 .coverage
 .idea
 .cache/
+.tox/
 build/
 
 # UI
diff --git a/mitmproxy/script/script.py b/mitmproxy/script/script.py
index 4ec9af975..9bf05f275 100644
--- a/mitmproxy/script/script.py
+++ b/mitmproxy/script/script.py
@@ -77,7 +77,7 @@ class Script(object):
         try:
             with open(self.filename) as f:
                 code = compile(f.read(), self.filename, 'exec')
-                exec (code, self.ns, self.ns)
+                exec(code, self.ns, self.ns)
         except Exception:
             six.reraise(
                 ScriptException,
diff --git a/setup.cfg b/setup.cfg
index 908dbe482..e83ca0abd 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -3,6 +3,7 @@ max-line-length = 140
 max-complexity = 25
 ignore = E251,C901
 exclude = mitmproxy/contrib/*,test/mitmproxy/data/*
+builtins = file,open,basestring,xrange,unicode,long,cmp
 
 [pytest]
 testpaths = test