diff --git a/src/net/http/transport.go b/src/net/http/transport.go
index 1854daba8a..b3fc08139c 100644
--- a/src/net/http/transport.go
+++ b/src/net/http/transport.go
@@ -38,8 +38,8 @@ import (
 // DefaultTransport is the default implementation of Transport and is
 // used by DefaultClient. It establishes network connections as needed
 // and caches them for reuse by subsequent calls. It uses HTTP proxies
-// as directed by the $HTTP_PROXY and $NO_PROXY (or $http_proxy and
-// $no_proxy) environment variables.
+// as directed by the environment variables HTTP_PROXY, HTTPS_PROXY
+// and NO_PROXY (or the lowercase versions thereof).
 var DefaultTransport RoundTripper = &Transport{
 	Proxy: ProxyFromEnvironment,
 	DialContext: defaultTransportDialContext(&net.Dialer{