diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 167a069b9c3d88db7a7442290f78145a5cbd9947..eb05c46a7bac6713182129d8750a4a9acc75ed12 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -200,9 +200,9 @@ sync-gitlab-spack-instance:
     - read-write
   image: $GITLAB_BUILD_ENV_DOCKER_IMAGE
   variables:
-    SPACK_NFS_ENV: $CI_COMMIT_BRANCH
     SPACK_REPO_PATH: $SPACK_PATH_GITLAB/ebrains-spack-builds
   script:
+    - SPACK_NFS_ENV=${CI_COMMIT_BRANCH//./-}
     # get latest state of EBRAINS repo
     - rm -rf $SPACK_REPO_PATH && cp -r $CI_PROJECT_DIR $SPACK_REPO_PATH
     # run installation script
@@ -233,11 +233,11 @@ test-gitlab-spack-instance:
     - read-write
   image: $GITLAB_BUILD_ENV_DOCKER_IMAGE
   variables:
-    SPACK_NFS_ENV: $CI_COMMIT_BRANCH
     SPACK_REPO_PATH: $SPACK_PATH_GITLAB/ebrains-spack-builds
     SPACK_USER_CACHE_PATH: $SPACK_PATH_GITLAB/spack/.spack
     SPACK_USER_CONFIG_PATH: $SPACK_PATH_GITLAB/spack/.spack
   script:
+    - SPACK_NFS_ENV=${CI_COMMIT_BRANCH//./-}
     - source $SPACK_PATH_GITLAB/spack/share/spack/setup-env.sh
     - spack env activate $SPACK_NFS_ENV
     # TODO: run all tests when test dependency issue is fixed