diff --git a/doc/manual/command-ref/nix-shell.xml b/doc/manual/command-ref/nix-shell.xml
index cb443c888..bb4a4e420 100644
--- a/doc/manual/command-ref/nix-shell.xml
+++ b/doc/manual/command-ref/nix-shell.xml
@@ -337,7 +337,7 @@ following Haskell script uses a specific branch of Nixpkgs/NixOS (the
 
 <programlisting><![CDATA[
 #! /usr/bin/env nix-shell
-#! nix-shell -i runghc -p haskellPackages.ghc haskellPackages.HTTP haskellPackages.tagsoup
+#! nix-shell -i runghc -p "haskellPackages.ghcWithPackages (ps: [ps.HTTP ps.tagsoup])"
 #! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-18.03.tar.gz
 
 import Network.HTTP