diff --git a/envsetup.sh b/envsetup.sh
index 793f4b6..d533d0d 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -599,7 +599,12 @@
 {
     local answer
 
-    if [ "$1" ] ; then
+    if [[ $# -gt 1 ]]; then
+        echo "usage: lunch [target]" >&2
+        return 1
+    fi
+
+    if [ "$1" ]; then
         answer=$1
     else
         print_lunch_menu