diff --git a/install.sh b/install.sh
index a95c4e8..8a114e0 100755
--- a/install.sh
+++ b/install.sh
@@ -329,21 +329,21 @@ choose_modules() {
 script_dir() {
   case "$0" in
     */*) cd "$(dirname "$0")" 2>/dev/null && pwd ;;
-    *) pwd ;;
+    *) return 1 ;;
   esac
 }
 
 download_file() {
   src="$1"
   dst="$2"
-  local_dir="$(script_dir)"
+  local_dir="$(script_dir 2>/dev/null || true)"
 
-  if [ -f "$local_dir/$src" ]; then
+  if [ -n "$local_dir" ] && [ -f "$local_dir/$src" ]; then
     run cp "$local_dir/$src" "$dst"
     return 0
   fi
 
-  if [ -f "$PWD/$src" ]; then
+  if [ "${LEMANA_VPN_USE_LOCAL_FILES:-0}" = "1" ] && [ -f "$PWD/$src" ]; then
     run cp "$PWD/$src" "$dst"
     return 0
   fi
diff --git a/tests/smoke.sh b/tests/smoke.sh
index cceffce..5c5fbb8 100755
--- a/tests/smoke.sh
+++ b/tests/smoke.sh
@@ -29,4 +29,19 @@ status_text="$(bash "$ROOT/bin/vpn-lemanapro.sh" --status)"
 printf '%s\n' "$status_text" | grep -q 'app='
 printf '%s\n' "$status_text" | grep -q 'autostart='
 
+fake_pwd="$TMP_DIR/fake-pwd"
+mkdir -p "$fake_pwd/bin"
+printf 'stale local cli\n' > "$fake_pwd/bin/vpn-lemanapro.sh"
+
+piped_output="$(
+  cd "$fake_pwd" &&
+    LEMANA_VPN_RAW_BASE_URL="file://$ROOT" sh -s -- --dry-run --non-interactive --minimal --without-app < "$ROOT/install.sh"
+)"
+
+printf '%s\n' "$piped_output" | grep -q "curl -fsSL file://$ROOT/bin/vpn-lemanapro.sh"
+if printf '%s\n' "$piped_output" | grep -q "$fake_pwd/bin/vpn-lemanapro.sh"; then
+  echo "piped install used stale PWD/bin/vpn-lemanapro.sh" >&2
+  exit 1
+fi
+
 printf 'smoke ok\n'