diff --git a/dither4.s b/dither4.s
index c98400b..7b88f84 100644
--- a/dither4.s
+++ b/dither4.s
@@ -135,7 +135,7 @@ each_scanline:
     pla
     tay
     iny
-    cpy height
+    cpy #height
     bne each_scanline
 
     jmp wait_start