diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 87b1eaf98d8590943cc34eaef2bdf5403eaca6fe..f3bed3538478397158663a93d3c3153b79d59959 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -2,6 +2,7 @@
 variables:
   GIT_SUBMODULE_STRATEGY: recursive
   HYPERTHREADING: "false"
+  OMP_NUM_THREADS: 1
 
 before_script:
   - echo "Running make concurrently with ${DUNECI_PARALLEL} cores, where possibly"