diff --git a/doc/install_and_upgrade.md b/doc/install_and_upgrade.md
index 3d48908c7b..b88a4f5ce4 100644
--- a/doc/install_and_upgrade.md
+++ b/doc/install_and_upgrade.md
@@ -328,6 +328,17 @@ package-indices:
    http: http://mirrors.tuna.tsinghua.edu.cn/hackage/00-index.tar.gz
 ```
 
+## Using an http proxy
+
+To use `stack` behind a http proxy with ip address *IP* and port *PORT*, first set up an environment variable `http_proxy` and then run the stack command. _e.g._
+
+```
+$ export http_proxy=IP:PORT
+$ stack install
+```
+
+Note that on most operating systems, it is not mandatory for programs to follow the "system-wide" http proxy. Some programs, such as browsers, do honor this "system-wide" http proxy setting, while other programs, including bash, do not. That means configuring "http proxy setting" in your Control Panel (Windows) or System Preferences (Mac) would not result in `stack` traffic going through the proxy. 
+
 ## Upgrade
 
 There are essentially four different approaches to upgrade: