diff --git a/Scripts/Tests/metatable.lua b/Scripts/Tests/metatable.lua
new file mode 100644
index 0000000..1d24c13
--- /dev/null
+++ b/Scripts/Tests/metatable.lua
@@ -0,0 +1,25 @@
+-- Should succeed
+-- User created tables can have their metatables changed
+setmetatable({},{})
+
+-- Should fail
+protectedTables = {
+	string,
+	math,
+	string,
+	table,
+	math,
+	coroutine,
+	os,
+}
+
+function modifyProtectedTable(t)
+	setmetatable(t, {})
+end
+
+for _, t in ipairs(protectedTables) do
+	local code, msg = pcall(modifyProtectedTable, t)
+	if(code ~= false or msg:match("cannot change a protected metatable$") == nil) then
+		print("ERROR: Protected table was modified!")
+	end
+end
\ No newline at end of file
diff --git a/Scripts/sandbox.lua b/Scripts/sandbox.lua
index 44b1219..ddf8bef 100644
--- a/Scripts/sandbox.lua
+++ b/Scripts/sandbox.lua
@@ -256,7 +256,27 @@ function sandbox.createNew(aiID, scriptName)
 	end
 	
 	sb.require = sb.dofile
+	
+	sb.setmetatable = setmetatable
+	sb.getmetatable = getmetatable
+	
+	protectMetatables(sb)
+	
 	return sb
 end
 
+function protectMetatables(t)
+	if type(t) ~= "table" then
+		return
+	end
+	
+	local metatable = getmetatable(t) or {}
+	metatable.__metatable=false -- Protect metatable, cannot be modified anymore
+	setmetatable(t, metatable)
+	
+	for _, v in pairs(t) do
+		protectMetatables(v)
+	end
+end
+
 return sandbox