diff --git a/lib/fetchers.nix b/lib/fetchers.nix
index 1107353b51dd..e94c611299be 100644
--- a/lib/fetchers.nix
+++ b/lib/fetchers.nix
@@ -8,6 +8,7 @@
     # derivation like fetchurl is allowed to do so since its result is
     # by definition pure.
     "http_proxy" "https_proxy" "ftp_proxy" "all_proxy" "no_proxy"
+    "HTTP_PROXY" "HTTPS_PROXY" "FTP_PROXY" "ALL_PROXY" "NO_PROXY"
   ];
 
 }