diff --git a/corepatchlua.lua b/corepatchlua.lua
new file mode 100644
index 0000000..b7f3bc9
--- /dev/null
+++ b/corepatchlua.lua
@@ -0,0 +1,25 @@
+local mt = getmetatable(_G)
+if mt == nil then
+	mt = {}
+	setmetatable(_G, mt)
+end
+mt.__declared = {}
+function mt.__newindex(t, n, v)
+	if not mt.__declared[n] then
+		local info = debug.getinfo(2, "S")
+		if info and info.what ~= "main" and info.what ~= "C" then
+			error("cannot assign undeclared global '" .. tostring(n) .. "'", 2)
+		end
+		mt.__declared[n] = true
+	end
+	rawset(t, n, v)
+end
+
+function mt.__index(t, n)
+	if not mt.__declared[n] then
+		local info = debug.getinfo(2, "S")
+		if info and info.what ~= "main" and info.what ~= "C" then
+			error("cannot use undeclared global '" .. tostring(n) .. "'", 2)
+		end
+	end
+end
\ No newline at end of file