diff --git a/utils/tests/gitlab-ci-doc.yml b/utils/tests/gitlab-ci-doc.yml
index aeb9a4d04..bf4c3e28f 100644
--- a/utils/tests/gitlab-ci-doc.yml
+++ b/utils/tests/gitlab-ci-doc.yml
@@ -41,6 +41,7 @@ doxygen:
     # Just need to check doc/introspected-command-line.h and doc/introspected-doxygen.h
     - python3 utils/check-style-clang-format.py --no-formatting --no-tabs doc/introspected-doxygen.h
     - python3 utils/check-style-clang-format.py --no-formatting --no-tabs doc/introspected-command-line.h
+    - ./ns3 clean
     # - doxygen doc/doxygen.conf
     # - mv doc/html/ public/doxygen
   cache: