diff --git a/pkgs/development/r-modules/README.md b/pkgs/development/r-modules/README.md
index cb962e138c5..0d9c1490d2b 100644
--- a/pkgs/development/r-modules/README.md
+++ b/pkgs/development/r-modules/README.md
@@ -87,6 +87,8 @@ this into your user profile.
 ## Updating the package set
 
 ```bash
+nix-shell generate-shell.nix
+
 Rscript generate-r-packages.R cran  > cran-packages.nix.new
 mv cran-packages.nix.new cran-packages.nix