diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 2041cd7dd31e724ab7b2e25f18ff83df42d184c1..659e863530229aff48c514d400a02ab3a64cb635 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -77,6 +77,7 @@ variables:
       ${apptainer_options}
          --cleanenv
          -H $(mktemp -d -p ${FAKEHOME}/):/home/$(id -un)
+         --env PYTHONUNBUFFERED=1
          --bind ${CI_DATA_LT}/buildcache:${MOUNT_POINT}/buildcache
          --bind ${CI_DATA_LT}/spack-mirror:${MOUNT_POINT}/spack-mirror
          --bind ${CI_DATA_ST}/squashfs-cache/:/squashfs-cache
diff --git a/ci/apptainer_by_hand.sh b/ci/apptainer_by_hand.sh
index 3c78972734af7c7c0a0b7efbba7c90e2aad85c25..21a7d68ddc0d10d242507d904faa90e4ef0b6d87 100755
--- a/ci/apptainer_by_hand.sh
+++ b/ci/apptainer_by_hand.sh
@@ -34,6 +34,7 @@ srun ${srun_options} --pty apptainer run \
     --bind ${CI_DATA_LT}/spack-mirror:${MOUNT_POINT}/spack-mirror \
     --bind ${CI_DATA_LT}/squashfs-cache/:/squashfs-cache \
     --bind ${CI_DATA_ST}/overlayfs:/overlayfs \
+    --env PYTHONUNBUFFERED=1 \
     --env stack=${stack} \
     --env environment=${environment} \
     --env GPG_PRIVATE_KEY=${GPG_PRIVATE_KEY} \