diff --git a/Engine.cc b/Engine.cc
index f423d25..621b545 100644
--- a/Engine.cc
+++ b/Engine.cc
@@ -256,6 +256,11 @@ int Engine::loadModel(const string & name, bool static_data, float scale)
     return 0;
 }
 
+bool Engine::isKeyDown(const std::string & key)
+{
+    return m_keysDown.find(key) != m_keysDown.end();
+}
+
 /* called by SDL when the update timer expires */
 Uint32 Engine::updateCallback(Uint32 interval, void * param)
 {
@@ -336,6 +341,10 @@ void Engine::update()
 
 void Engine::key_event(int keysym, bool pressed)
 {
+    if (pressed)
+        m_keysDown[sdl_keymap[keysym]] = true;
+    else
+        m_keysDown.erase(sdl_keymap[keysym]);
     lua_getfield(m_luaState, LUA_GLOBALSINDEX,
             pressed ? "key_pressed_event" : "key_released_event");
     if (lua_type(m_luaState, -1) == LUA_TFUNCTION)
diff --git a/Engine.h b/Engine.h
index 653b703..032c4f4 100644
--- a/Engine.h
+++ b/Engine.h
@@ -84,6 +84,7 @@ class Engine
         void endFrame();
         int loadModel(const std::string & name, bool static_data,
                 float scale = 1.0f);
+        bool isKeyDown(const std::string & key);
 
         /* lua services */
         int setCamera(lua_State * L);
@@ -119,6 +120,7 @@ class Engine
         bool            m_autoStartFrame;
         bool            m_autoEndFrame;
         bool            m_autoDrawObjects;
+        std::map<std::string, bool> m_keysDown;
 };
 
 extern Engine * g_engine;
diff --git a/ag.cc b/ag.cc
index ffba979..13d1a72 100644
--- a/ag.cc
+++ b/ag.cc
@@ -36,6 +36,7 @@ namespace ag
             { "setAutoStartFrame", setAutoStartFrame },
             { "setAutoEndFrame", setAutoEndFrame },
             { "setAutoDrawObjects", setAutoDrawObjects },
+            { "isKeyDown", isKeyDown },
             { NULL, NULL }
         };
         luaL_register(L, "ag", functions);
@@ -245,6 +246,16 @@ namespace ag
         return 0;
     }
 
+    int isKeyDown(lua_State * L)
+    {
+        int argc = lua_gettop(L);
+        if (argc == 1 && lua_isstring(L, 1))
+            lua_pushboolean(L, g_engine->isKeyDown(lua_tostring(L, 1)));
+        else
+            lua_pushboolean(L, false);
+        return 1;
+    }
+
     namespace object
     {
         static Engine::Object * getObject(lua_State * L, int index)
diff --git a/ag.h b/ag.h
index 9fd8d02..557f395 100644
--- a/ag.h
+++ b/ag.h
@@ -22,6 +22,7 @@ namespace ag
     int setAutoStartFrame(lua_State * L);
     int setAutoEndFrame(lua_State * L);
     int setAutoDrawObjects(lua_State * L);
+    int isKeyDown(lua_State * L);
 
     namespace object
     {
diff --git a/tests/ballstairs.lua b/tests/ballstairs.lua
index 7afb271..a79ff62 100755
--- a/tests/ballstairs.lua
+++ b/tests/ballstairs.lua
@@ -2,6 +2,9 @@
 function update_event()
     ballx, bally, ballz = ball:getPosition()
     ag.setCamera(7, -6, 15, ballx, bally, ballz, 0, 0, 1)
+    if (ag.isKeyDown("m")) then
+        ball:setPosition(-7, 7.4, 12)
+    end
 end
 
 function key_pressed_event(key)