diff --git a/res/content/base/package.json b/res/content/base/package.json
index 249dd4ee..7da43458 100644
--- a/res/content/base/package.json
+++ b/res/content/base/package.json
@@ -1,6 +1,6 @@
 {
     "id": "base",
     "title": "Base",
-    "version": "0.19",
+    "version": "0.20",
     "description": "basic content package"
 }
diff --git a/src/constants.h b/src/constants.h
index 56f54c7f..fffa9c22 100644
--- a/src/constants.h
+++ b/src/constants.h
@@ -2,10 +2,13 @@
 #define SRC_CONSTANTS_H_
 
 #include <limits>
+#include <string>
 #include "typedefs.h"
 
 const int ENGINE_VERSION_MAJOR = 0;
-const int ENGINE_VERSION_MINOR = 19;
+const int ENGINE_VERSION_MINOR = 20;
+const bool ENGINE_VERSION_INDEV = true;
+#define ENGINE_VERSION_STRING "0.20"
 
 const int BLOCK_AIR = 0;
 const int ITEM_EMPTY = 0;
diff --git a/src/engine.cpp b/src/engine.cpp
index 80d9114a..54ae6876 100644
--- a/src/engine.cpp
+++ b/src/engine.cpp
@@ -75,6 +75,9 @@ Engine::Engine(EngineSettings& settings, EnginePaths* paths)
 	gui = std::make_unique<gui::GUI>();
     if (settings.ui.language == "auto") {
         settings.ui.language = langs::locale_by_envlocale(platform::detect_locale(), paths->getResources());
+    }
+	if (ENGINE_VERSION_INDEV) {
+		menus::create_version_label(this);
     }
     setLanguage(settings.ui.language);
 }
diff --git a/src/frontend/menu.cpp b/src/frontend/menu.cpp
index ce1ab9cc..0879978f 100644
--- a/src/frontend/menu.cpp
+++ b/src/frontend/menu.cpp
@@ -82,6 +82,20 @@ static std::shared_ptr<Button> create_button(
     return btn;
 }
 
+
+void menus::create_version_label(Engine* engine) {
+    auto gui = engine->getGUI();
+    auto vlabel = std::make_shared<gui::Label>(
+        util::str2wstr_utf8(ENGINE_VERSION_STRING " development build ")
+    );
+    vlabel->setZIndex(1000);
+    vlabel->setColor(glm::vec4(1, 1, 1, 0.5f));
+    vlabel->setPositionFunc([=]() {
+        return glm::vec2(Window::width-vlabel->getSize().x, 2);
+    });
+    gui->add(vlabel);
+}
+
 static void show_content_missing(
     Engine* engine, 
     const Content* content, 
diff --git a/src/frontend/menu.h b/src/frontend/menu.h
index 08cd3b2b..756b19a9 100644
--- a/src/frontend/menu.h
+++ b/src/frontend/menu.h
@@ -4,6 +4,7 @@
 class Engine;
 
 namespace menus {
+    void create_version_label(Engine* engine);
     void create_menus(Engine* engine);
     void refresh_menus(Engine* engine);
 }
diff --git a/src/logic/scripting/lua/LuaState.cpp b/src/logic/scripting/lua/LuaState.cpp
index 68fe1ebd..0b870f92 100644
--- a/src/logic/scripting/lua/LuaState.cpp
+++ b/src/logic/scripting/lua/LuaState.cpp
@@ -11,7 +11,19 @@
 lua::luaerror::luaerror(const std::string& message) : std::runtime_error(message) {
 }
 
+void lua::LuaState::removeLibFuncs(const char* libname, const char* funcs[]) {
+    if (getglobal(libname)) {
+        for (uint i = 0; funcs[i]; i++) {
+            pushnil();
+            setfield(funcs[i], -2);
+        }
+    }
+}
+
 lua::LuaState::LuaState() {
+    std::cout << LUA_VERSION << std::endl;
+    std::cout << LUAJIT_VERSION << std::endl;
+
     L = luaL_newstate();
     if (L == nullptr) {
         throw lua::luaerror("could not to initialize Lua");
@@ -25,10 +37,19 @@ lua::LuaState::LuaState() {
     luaopen_jit(L);
     luaopen_bit(L);
 
-    std::cout << LUA_VERSION << std::endl;
-    std::cout << LUAJIT_VERSION << std::endl;
+    luaopen_os(L);
+    const char* removed_os[] {
+        "execute",
+        "exit",
+        "remove",
+        "rename",
+        "setlocale",
+        "tmpname",
+        nullptr
+    };
+    removeLibFuncs("os", removed_os);
 
-    createFuncs();
+    createLibs();
 
     lua_pushvalue(L, LUA_GLOBALSINDEX);
     setglobal(envName(0));
@@ -94,7 +115,7 @@ void lua::LuaState::remove(const std::string& name) {
     lua_setglobal(L, name.c_str());
 }
 
-void lua::LuaState::createFuncs() {
+void lua::LuaState::createLibs() {
     openlib("pack", packlib, 0);
     openlib("world", worldlib, 0);
     openlib("player", playerlib, 0);
diff --git a/src/logic/scripting/lua/LuaState.h b/src/logic/scripting/lua/LuaState.h
index b80d2aab..319ee280 100644
--- a/src/logic/scripting/lua/LuaState.h
+++ b/src/logic/scripting/lua/LuaState.h
@@ -21,6 +21,9 @@ namespace lua {
 
         void logError(const std::string& text);
         void initEnvironment();
+
+        void removeLibFuncs(const char* libname, const char* funcs[]);
+        void createLibs();
     public:
         LuaState();
         ~LuaState();
@@ -55,7 +58,6 @@ namespace lua {
         bool hasglobal(const std::string& name);
         bool rename(const std::string& from, const std::string& to);
         void remove(const std::string& name);;
-        void createFuncs();
         int createEnvironment(int parent);
         void removeEnvironment(int id);
         const std::string storeAnonymous();