diff --git a/README.md b/README.md
index 27624e8ddff5e36a45d58508f5bc8d0f6fae01a5..d8ec1311359fc5eea1f87f2367c90035903693b2 100644
--- a/README.md
+++ b/README.md
@@ -16,11 +16,15 @@ is built using Jekyll.
    ```bash
    bundle install
    ```
-4. Build and preview the web page.
+4. Install submodules (currently `bootstrap`, `Font-Awesome`, `jquery`, `MathJax`).
+   ``` bash
+   git submodule update --init --recursive
+   ```
+5. Build and preview the web page.
    ```bash
    bundle exec jekyll serve --future
    ```
-5. Add content.
+6. Add content.
 
 Execute the commands above from the root of your repository.