diff --git a/README.md b/README.md
index 4ecd9a5..2e8daa3 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,10 @@
 
 ## Getting Started 
 
+This mod needs access to an insecure environment in order to work.
+
+Add `formspec_edit` to `secure.trusted_mods` in your `minetest.conf` file.
+
 The file *formspec.spec* in your:
 
 ```minetest_folder/games/formspec_editor/mods/formspec_edit```
diff --git a/mods/formspec_edit/init.lua b/mods/formspec_edit/init.lua
index 5a38e08..7467797 100644
--- a/mods/formspec_edit/init.lua
+++ b/mods/formspec_edit/init.lua
@@ -9,7 +9,12 @@ minetest.register_alias("mapgen_water_source", "air")
 
 --Variables
 local modpath = minetest.get_modpath("formspec_edit")
+
 local insecure_env = minetest.request_insecure_environment()
+if not insecure_env then
+	error("[formspec_editor] Cannot access insecure environment!")
+end
+
 local io = insecure_env.io
 local update_time = tonumber(minetest.settings:get("formspec_editor.update_time")) or 0.2