diff --git a/github/Requester.py b/github/Requester.py
index 0d2527f0..ff106971 100644
--- a/github/Requester.py
+++ b/github/Requester.py
@@ -326,12 +326,10 @@ class Requester:
         ## set.
         ## http_proxy: http://user:password@proxy_host:proxy_port
         ##
-        try:
-           proxy_uri = os.getenv('http_proxy')
-        except:
-           proxy_uri = None
-
-        if (proxy_uri != None):
+        proxy_uri = os.getenv('http_proxy')
+        if proxy_uri is None:
+            proxy_uri = os.getenv('HTTP_PROXY')
+        if proxy_uri is not None:
             url = urlparse.urlparse(proxy_uri)
             conn = self.__connectionClass(url.hostname, url.port, **kwds)
             headers = {}