diff --git a/Chapter_2/Hello_Triangle/Hello_Triangle.c b/Chapter_2/Hello_Triangle/Hello_Triangle.c
index f67baf0..dfd031e 100644
--- a/Chapter_2/Hello_Triangle/Hello_Triangle.c
+++ b/Chapter_2/Hello_Triangle/Hello_Triangle.c
@@ -175,7 +175,7 @@ int Init ( ESContext *esContext )
 //
 void Draw ( ESContext *esContext )
 {
-   UserData *userData = esContext->userData;
+   UserData *userData = (UserData *) esContext->userData;
    GLfloat vVertices[] = {  0.0f,  0.5f, 0.0f,
                             -0.5f, -0.5f, 0.0f,
                             0.5f, -0.5f, 0.0f
@@ -199,7 +199,7 @@ void Draw ( ESContext *esContext )
 
 void Shutdown ( ESContext *esContext )
 {
-   UserData *userData = esContext->userData;
+   UserData *userData = (UserData *) esContext->userData;
 
    glDeleteProgram ( userData->programObject );
 }