diff --git a/ponydos.asm b/ponydos.asm
index b9c4735..157fa1a 100644
--- a/ponydos.asm
+++ b/ponydos.asm
@@ -108,9 +108,8 @@ mainloop:
 	shr bx, 1
 	mov cx, [di - mouse_column + mouse_y]
 	shr cx, 2
-	cmp [di], bl
-	jne .update_cursor
-	cmp [di - mouse_column + mouse_row], cl
+	mov bh, cl
+	cmp [di], bx
 	jne .update_cursor
 
 	hlt
@@ -118,8 +117,7 @@ mainloop:
 
 	.update_cursor:
 		call flip_mouse_cursor
-		mov [di], bl
-		mov [di - mouse_column + mouse_row], cl
+		mov [di], bx
 		call flip_mouse_cursor
 		jmp mainloop
 
@@ -488,7 +486,7 @@ mouse_y resw 1 ; mouse_x + 2, do not touch
 mouse_buttons resb 1
 
 mouse_column resb 1
-mouse_row resb 1
+mouse_row resb 1 ; mouse_column + 1
 
 window_chain_head resw 1
 redraw resb 1