diff --git a/.github/workflows/build_docs.yml b/.github/workflows/build_docs.yml
index 58c77f00..fe8fbedd 100644
--- a/.github/workflows/build_docs.yml
+++ b/.github/workflows/build_docs.yml
@@ -13,7 +13,7 @@
      strategy:
        matrix:
          os: ['ubuntu-latest']
-         environment-file: [ci/39.yml]
+         environment-file: [ci/39.yaml]
          experimental: [false]
      defaults:
        run: