diff --git a/.github/workflows/validate-frontmatter.yml b/.github/workflows/validate-frontmatter.yml
index dc2ea6a..243455d 100644
--- a/.github/workflows/validate-frontmatter.yml
+++ b/.github/workflows/validate-frontmatter.yml
@@ -17,7 +17,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - uses: oven-sh/setup-bun@v2
+      - uses: oven-sh/setup-bun@0c5077e51419868618aeaa5fe8019c62421857d6 # v2.2.0 (sha-pinned)
 
       - name: Install dependencies
         run: cd .github/scripts && bun install yaml