diff --git a/pkgs/development/compilers/ghcjs-ng/README.md b/pkgs/development/compilers/ghcjs-ng/README.md
index 6292f0cd4d23..99ad980c965e 100644
--- a/pkgs/development/compilers/ghcjs-ng/README.md
+++ b/pkgs/development/compilers/ghcjs-ng/README.md
@@ -16,6 +16,6 @@ $ nix-prefetch-git https://github.com/ghcjs/ghcjs --rev refs/heads/ghc-8.4 \
   | jq '{ url, rev, fetchSubmodules, sha256 }' \
   > 8.4/git.json
 $ cat $(nix-build ../../../.. -A haskell.compiler.ghcjs82.genStage0 --no-out-link) > 8.4/stage0.nix
-$ cabal2nix git://github.com/ghcjs/ghcjs-base > ghcjs-base.nix
+$ cabal2nix --compiler ghcjs git://github.com/ghcjs/ghcjs-base > ghcjs-base.nix
 ```