diff --git a/setup-min.sh b/setup-min.sh
index 8e3eebf..6ed3305 100644
--- a/setup-min.sh
+++ b/setup-min.sh
@@ -12,7 +12,15 @@
 # curl -fsSL https://example.com/setup-min.bash | bash
 # wget -nv https://example.com/setup-min.bash -O - | bash
 
-if [ -z "$NODE_PATH" ]; then
+set -e
+set -u
+set -o pipefail
+
+if [ -z "${PREFIX-}" ]; then
+  PREFIX=""
+fi
+
+if [ -n "$NODE_PATH" ]; then
   node_install_path=$(dirname $(dirname $NODE_PATH))
 else
   node_install_path=$PREFIX/usr/local