diff --git a/.github/workflows/book.yml b/.github/workflows/book.yml
index 69c7b07c..5f20c520 100644
--- a/.github/workflows/book.yml
+++ b/.github/workflows/book.yml
@@ -16,6 +16,12 @@ jobs:
         with:
           mdbook-version: '0.4.4'
 
+      - name: Install mdbook-katex
+        uses: actions-rs/cargo@v1
+        with:
+          command: install
+          args: mdbook-katex
+
       - name: Build Orchard book
         run: mdbook build book/
 
diff --git a/book/book.toml b/book/book.toml
index 9c221ca0..e86492cb 100644
--- a/book/book.toml
+++ b/book/book.toml
@@ -4,3 +4,5 @@ language = "en"
 multilingual = false
 src = "src"
 title = "The Orchard Book"
+
+[preprocessor.katex]