diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ab3ae810..db2d2162 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -23,7 +23,7 @@ jobs:
         run: |
           mkdir -p build
           cd build
-          cmake -DDISABLE_ALL=ON -DBUILD_DOC=ON ..
+          cmake -DDISABLE_ALL=ON -DBUILD_DOC=ON -DSPHINX_FLAGS="-W" ..
           make doc
 
   ipc: