diff --git a/.github/workflows/mdbook.yml b/.github/workflows/mdbook.yml
index c9e8929..3def6da 100644
--- a/.github/workflows/mdbook.yml
+++ b/.github/workflows/mdbook.yml
@@ -37,13 +37,14 @@ jobs:
       - name: Install mdbook.
         run: |
           mkdir bin
-          curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.35/mdbook-v0.4.35-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
+          curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.4.28/mdbook-v0.4.28-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
       - name: Install mdbook-katex.
         run: |
           cargo install mdbook-katex
       - name: Install mdbook-admonish.
         run: |
-          cargo install mdbook-admonish --locked
+          cargo install mdbook-admonish
+          mdbook-admonish install
       - name: Install mdbook-toc.
         run: |
           cargo install mdbook-toc