diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index b21002bae..01ecc0f1a 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -21,7 +21,7 @@ jobs:
       run: cp -R /orig/${{matrix.version}} orig
     - name: Build
       run: |
-        python configure.py --version ${{matrix.version}} --compilers /compilers
+        python configure.py --version ${{matrix.version}} --compilers /compilers --warn error
         ninja
     - name: Upload progress
       if: github.ref == 'refs/heads/main'