diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index a6d5951920a1b2106ec3f53ede21b7e755f64296..b9afc2ad648601e55a9b71c0534d8fbb5629ae64 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1916,6 +1916,7 @@ mac_MpiOnly_Dbg:
       WALBERLA_BUILD_WITH_MPI: "ON"
       WALBERLA_BUILD_WITH_OPENMP: "OFF"
       WALBERLA_BUILD_WITH_PYTHON: "ON"
+      OMPI_MCA_btl_vader_backing_directory: "/tmp"
    except:
       variables:
          - $DISABLE_PER_COMMIT_BUILDS
@@ -1928,6 +1929,7 @@ mac_MpiOnly:
       WALBERLA_BUILD_WITH_MPI: "ON"
       WALBERLA_BUILD_WITH_OPENMP: "OFF"
       WALBERLA_BUILD_WITH_PYTHON: "ON"
+      OMPI_MCA_btl_vader_backing_directory: "/tmp"
    except:
       variables:
          - $DISABLE_PER_COMMIT_BUILDS