diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 60d8123faec45431aa1aa22b930a781e295608fc..a489bb8daefd5d3c77e528b3b6f54bbe004a1f5e 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -34,6 +34,7 @@ stages:
       - cd $CI_PROJECT_DIR/build
       - if dpkg --compare-versions `ompi_info | head -2 | tail -1 | sed 's/[^0-9.]*\([0-9.]*\).*/\1/'` ge 1.10; then export MPIEXEC_PREFLAGS="--allow-run-as-root" ; fi
       - cmake ..
+        -DCMAKE_CXX_FLAGS=$CMAKE_CXX_FLAGS
         -DWALBERLA_BUFFER_DEBUG=$WALBERLA_BUFFER_DEBUG
         -DWALBERLA_BUILD_TESTS=ON
         -DWALBERLA_BUILD_BENCHMARKS=ON