diff --git a/src/doc/rustc-dev-guide/README.md b/src/doc/rustc-dev-guide/README.md
index 42e7e44a4b5f..a5481e82c7fa 100644
--- a/src/doc/rustc-dev-guide/README.md
+++ b/src/doc/rustc-dev-guide/README.md
@@ -72,7 +72,8 @@ To make a PR, the following steps are useful.
 git submodule update --remote src/doc/rustc-guide
 git add -u
 git commit -m "Update rustc-guide"
-./x.py test -i --stage 1 src/doc/rustc-guide # This is optional and should succeed anyway
+# Note that you can use -i, which is short for --incremental, in the following command
+./x.py test --incremental --stage 1 src/doc/rustc-guide # This is optional and should succeed anyway
 # Open a PR in rust-lang/rust
 ```