diff --git a/src/app.rs b/src/app.rs
index b7b4bda..e842913 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -5,6 +5,10 @@ use piston::*;
 use board::Board;
 use number_renderer::NumberRenderer;
 use settings::Settings;
+use opengl_graphics::{
+    Gl,
+    Texture,
+};
 
 pub struct App<'a> {
     board: Board<'a>,
diff --git a/src/board.rs b/src/board.rs
index 4a7372f..647d7c8 100644
--- a/src/board.rs
+++ b/src/board.rs
@@ -4,6 +4,9 @@ use std::collections::hashmap::HashSet;
 use std::rand::random;
 use graphics::*;
 use piston::*;
+use opengl_graphics::{
+    Gl,
+};
 use number_renderer::NumberRenderer;
 use settings::Settings;
 use tile::{
diff --git a/src/main.rs b/src/main.rs
index 3e4f229..2d79d20 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,8 +5,11 @@ extern crate serialize;
 
 extern crate graphics;
 extern crate piston;
+extern crate opengl_graphics;
+extern crate sdl2_game_window;
 
 use piston::*;
+use sdl2_game_window::GameWindowSDL2;
 
 mod app;
 mod board;
diff --git a/src/number_renderer.rs b/src/number_renderer.rs
index 4d7a8c1..910b877 100644
--- a/src/number_renderer.rs
+++ b/src/number_renderer.rs
@@ -3,6 +3,10 @@ use graphics::*;
 use piston::{
     AssetStore,
 };
+use opengl_graphics::{
+    Gl,
+    Texture,
+};
 
 static DIGITS_WIDTH: f64 = 20.0;
 static DIGITS_HEIGHT: f64 = 26.0;
diff --git a/src/tile.rs b/src/tile.rs
index 45aa1ce..d7152c3 100644
--- a/src/tile.rs
+++ b/src/tile.rs
@@ -1,6 +1,7 @@
 
 use graphics::*;
 use piston::*;
+use opengl_graphics::Gl;
 use number_renderer::NumberRenderer;
 use settings::Settings;