diff --git a/installer/nixos-rebuild.sh b/installer/nixos-rebuild.sh
index f63264cedae..12fae0cc80a 100644
--- a/installer/nixos-rebuild.sh
+++ b/installer/nixos-rebuild.sh
@@ -51,3 +51,13 @@ fi
 if test "$action" = "switch" -o "$action" = "boot" -o "$action" = "test"; then
     $pathToConfig/bin/switch-to-configuration "$action"
 fi
+
+
+if test "$action" = "test"; then
+    cat >&2 <<EOF
+
+Warning: if you remove the symlink \`$pathToConfig', the active system
+configuration may be garbage collected!  This may render the system
+inoperable (though a reboot will fix things).
+EOF
+fi