diff --git a/doc/manual/src/advanced-topics/distributed-builds.md b/doc/manual/src/advanced-topics/distributed-builds.md
index 580b36736..c4c60db15 100644
--- a/doc/manual/src/advanced-topics/distributed-builds.md
+++ b/doc/manual/src/advanced-topics/distributed-builds.md
@@ -53,8 +53,8 @@ example, the following command allows you to build a derivation for
 $ uname
 Linux
 
-$ nix build \
-  '(with import <nixpkgs> { system = "x86_64-darwin"; }; runCommand "foo" {} "uname > $out")' \
+$ nix build --impure \
+  --expr '(with import <nixpkgs> { system = "x86_64-darwin"; }; runCommand "foo" {} "uname > $out")' \
   --builders 'ssh://mac x86_64-darwin'
 [1/0/1 built, 0.0 MiB DL] building foo on ssh://mac