diff --git a/requests/sessions.py b/requests/sessions.py
index ae4bcc8e79..4854fd469d 100644
--- a/requests/sessions.py
+++ b/requests/sessions.py
@@ -527,7 +527,7 @@ def request(self, method, url,
         )
         prep = self.prepare_request(req)
 
-        proxies = proxies or {}
+        proxies = proxies or self.proxies
 
         settings = self.merge_environment_settings(
             prep.url, proxies, stream, verify, cert