diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 636b1c4d..227550f5 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -8,6 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     env:
       MDBOOK_VERSION: 0.5.1
+      MDBOOK_OUTPUT__LINKCHECK__WARNING_POLICY: error
       RUN_BLACKSMITH: 1
     steps:
       - uses: actions/checkout@v4