diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 100c8090445b6b2681c8748516c5fa36cad46227..d63b2caa56ca46160aaf755b7037bb70d7e2facb 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,7 +1,7 @@
 run_tests:
   image: "python:$VERSION"
   script:
-    - apt update && apt install graphviz
+    - apt update && apt install -y graphviz
     - pip install -e .[dev]
     - export PYTHONPATH="$(pwd)"
     - coverage run --source . run_tests.py