diff --git a/contrib/build-ceph-base.sh b/contrib/build-ceph-base.sh
index f22b276c6..7f15a37b5 100644
--- a/contrib/build-ceph-base.sh
+++ b/contrib/build-ceph-base.sh
@@ -6,6 +6,7 @@ set -Eeuo pipefail
 # script. Dry runs will output commands that they would have executed as info messages.
 
 SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null && pwd )"
+PRERELEASE="${PRERELEASE:-false}"
 # shellcheck disable=SC1090  # sourcing from a variable here does indeed work
 source "${SCRIPT_DIR}/ceph-build-config.sh"