diff --git a/install.sh b/install.sh
index 2ac593d..fa604be 100755
--- a/install.sh
+++ b/install.sh
@@ -289,7 +289,7 @@ fi
 echo "${_endgroup}"
 
 echo "${_group}Setting up database ..."
-if [[ -n "$CI" || "$SKIP_USER_PROMPT" == 1 ]]; then
+if [[ -n "${CI:-''}" || "${SKIP_USER_PROMPT:-0}" == 1 ]]; then
   $dcr web upgrade --noinput
   echo ""
   echo "Did not prompt for user creation due to non-interactive shell."