diff --git a/sysdata/programs/horizon/src/main.hb b/sysdata/programs/horizon/src/main.hb
index 37cad69bc..198307fc4 100644
--- a/sysdata/programs/horizon/src/main.hb
+++ b/sysdata/programs/horizon/src/main.hb
@@ -133,7 +133,12 @@ main := fn(): int {
 			render.put_rect(screen, .(0, 0), .(screen.width - 1, screen.height - 1), render.white)
 
 			// render mouse
-			render.put_rect(screen, .(mouse_x, mouse_y), .(20, 20), render.white)
+			lum := render.indexptr(screen, mouse_x, mouse_y)
+			if lum.r / 3 + lum.g / 3 + lum.b / 3 < 128 {
+				render.put_rect(screen, .(mouse_x, mouse_y), .(20, 20), render.white)
+			} else {
+				render.put_rect(screen, .(mouse_x, mouse_y), .(20, 20), render.black)
+			}
 			// Send events to focused window
 		}