diff --git a/doc/build-helpers/fetchers.chapter.md b/doc/build-helpers/fetchers.chapter.md
index 2167df3f1748..21cadfaa21fa 100644
--- a/doc/build-helpers/fetchers.chapter.md
+++ b/doc/build-helpers/fetchers.chapter.md
@@ -157,6 +157,12 @@ Here are security considerations for this scenario:
 
   In more concrete terms, if you use any other hash, the [`--insecure` flag](https://curl.se/docs/manpage.html#-k) will be passed to the underlying call to `curl` when downloading content.
 
+## Proxy usage {#sec-pkgs-fetchers-proxy}
+
+Nixpkgs fetchers can make use of a http(s) proxy. Each fetcher will automatically inherit proxy-related environment variables (`http_proxy`, `https_proxy`, etc) via [impureEnvVars](https://nixos.org/manual/nix/stable/language/advanced-attributes#adv-attr-impureEnvVars).
+
+The environment variable `NIX_SSL_CERT_FILE` is also inherited in fetchers, and can be used to provide a custom certificate bundle to fetchers. This is usually required for a https proxy to work without certificate validation errors.
+
 []{#fetchurl}
 ## `fetchurl` {#sec-pkgs-fetchers-fetchurl}