diff --git a/scripts/ci/docker_registry_auth.sh b/scripts/ci/docker_registry_auth.sh
index 4c29ae8dfdab2c4d0480d3a558d6d18ee8e68715..e015acf52ccca7b050d36259bdecbf8159dc35f4 100755
--- a/scripts/ci/docker_registry_auth.sh
+++ b/scripts/ci/docker_registry_auth.sh
@@ -27,8 +27,8 @@ echo "CI_DOCKER_HUB=${CI_DOCKER_HUB:-}"
 echo "CI_PROJECT_NAME=${CI_PROJECT_NAME}"
 echo "CI_PROJECT_NAMESPACE=${CI_PROJECT_NAMESPACE}"
 echo "IMAGE_ARCH_PREFIX=${IMAGE_ARCH_PREFIX:-}"
-echo "DOCKER_BUILD_TARGET=${DOCKER_BUILD_TARGET}"
-echo "RUST_TOOLCHAIN_IMAGE=${RUST_TOOLCHAIN_IMAGE}"
+echo "DOCKER_BUILD_TARGET=${DOCKER_BUILD_TARGET:-}"
+echo "RUST_TOOLCHAIN_IMAGE=${RUST_TOOLCHAIN_IMAGE:-}"
 
 # CI_DOCKER_HUB is used to switch to Docker Hub if credentials are available with CI_DOCKER_AUTH
 # /!\ CI_DOCKER_HUB can be unset, CI_DOCKER_AUTH is only available on protected branches