diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index fc791e00824c4dfafbfc8cce7f053acd9322b913..b7ebab505794ec98e8bf73be97fb766cce6e2d5b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -67,7 +67,7 @@ documentation:static:
     name: rust
   stage: documentation
   rules:
-    - if: $CI_DEFAULT_BRANCH
+    - if: '$CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH'
   script:
   - mdbook build documentation --dest-dir public
   artifacts: