diff --git a/scrapy/settings/__init__.py b/scrapy/settings/__init__.py
index b8ae32d7c..951d91e8c 100644
--- a/scrapy/settings/__init__.py
+++ b/scrapy/settings/__init__.py
@@ -82,7 +82,8 @@ class BaseSettings(MutableMapping):
     def __init__(self, values=None, priority='project'):
         self.frozen = False
         self.attributes = {}
-        self.update(values, priority)
+        if values:
+            self.update(values, priority)
 
     def __getitem__(self, opt_name):
         if opt_name not in self: