diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 543e11f7f3241a69fa4b3a71924a7d9914fd5424..8643562df98aa178be5cc0be8f086c6d5013f4c6 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -63,7 +63,7 @@ full:
       - $ENABLE_NIGHTLY_BUILDS
   image: i10git.cs.fau.de:5005/pycodegen/pycodegen/full
   script:
-    - apt install ninja-build
+    - apt install -y ninja-build
     - python -m pip install -e .
     - python setup.py test
     - python setup.py doctest