diff --git a/install/alpine-tinyauth-install.sh b/install/alpine-tinyauth-install.sh
index e150e15e..f44cd5a1 100644
--- a/install/alpine-tinyauth-install.sh
+++ b/install/alpine-tinyauth-install.sh
@@ -61,9 +61,9 @@ pidfile="/var/run/tinyauth.pid"
 
 start_pre() {
   if [ -f "/opt/tinyauth/.env" ]; then
-    while IFS= read -r line || [ -n "${line-}" ]; do
-      [ -z "${line-}" ] && continue
-      case "${line-}" in
+    while IFS= read -r line || [ -n "${line:-}" ]; do
+      [ -z "${line:-}" ] && continue
+      case "${line:-}" in
         '#'*)
           continue
           ;;