diff --git a/main.c b/main.c
index 2fbcb65..8cc9612 100644
--- a/main.c
+++ b/main.c
@@ -27,6 +27,9 @@
 
 #define OTLEN	256
 
+#define SCREENWIDTH		320
+#define SCREENHEIGHT	240
+
 #define NUMVERTEXNORMALS	162
 static int anorms[NUMVERTEXNORMALS][3] = {
 #include "ps1anorms.h"
@@ -93,12 +96,12 @@ void init(void)
 	ResetGraph(0);
 	
 	// Define display environments, first on top and second on bottom
-	SetDefDispEnv(&disp[0], 0, 0, 320, 240);
-	SetDefDispEnv(&disp[1], 0, 240, 320, 240);
+	SetDefDispEnv(&disp[0], 0, 0, SCREENWIDTH, SCREENHEIGHT);
+	SetDefDispEnv(&disp[1], 0, SCREENHEIGHT, SCREENWIDTH, SCREENHEIGHT);
 	
 	// Define drawing environments, first on bottom and second on top
-	SetDefDrawEnv(&draw[0], 0, 240, 320, 240);
-	SetDefDrawEnv(&draw[1], 0, 0, 320, 240);
+	SetDefDrawEnv(&draw[0], 0, SCREENHEIGHT, SCREENWIDTH, SCREENHEIGHT);
+	SetDefDrawEnv(&draw[1], 0, 0, SCREENWIDTH, SCREENHEIGHT);
 	
 	// Set and enable clear color
 	setRGB0(&draw[0], 96, 0, 96);