diff --git a/shell/main.sh b/shell/main.sh
index a286723..7925a6f 100644
--- a/shell/main.sh
+++ b/shell/main.sh
@@ -1,4 +1,4 @@
-[ "${ENV}" ] || export ENV="/etc/shell/main.sh"
+[ -n "${ENV}" ] || export ENV="/etc/shell/main.sh"
 
 main_env_root() {
 	dirname "${ENV}"