diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d7aa7f24cd0d5af3f726e5ded07c8f2e04e56c58..efb24de0f82713e50803daa627e6d8c27e1c8de4 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -379,7 +379,7 @@ install-clang-8:
   script:
     - mkdir -p build
     - cd build
-    - cmake .. -DCMAKE_BUILD_TYPE=Release -DUSE_Pythia8_C8=C8
+    - cmake .. -DCMAKE_INSTALL_PREFIX=$PWD/install -DCMAKE_BUILD_TYPE=Release -DUSE_Pythia8_C8=C8
     - cmake --build . -- -j4
     - set -o pipefail
     - ctest -j4