diff --git a/xmas_2018/ball.s b/xmas_2018/ball.s
index e39520c7..f02b89da 100644
--- a/xmas_2018/ball.s
+++ b/xmas_2018/ball.s
@@ -242,7 +242,7 @@ ball_done:
 	rts						; 6
 
 
-.include "gr_scroll.s"
-greets:
-.incbin "greets.raw.lz4t"
-greets_end:
+;.include "gr_scroll.s"
+;greets:
+;.incbin "greets.raw.lz4t"
+;greets_end:
diff --git a/xmas_2018/delay_a.s b/xmas_2018/delay_a.s
index 2d0802da..62c4b1b6 100644
--- a/xmas_2018/delay_a.s
+++ b/xmas_2018/delay_a.s
@@ -5,6 +5,7 @@
 ; The branches must not cross page boundaries!
 ;
 
+delay_begin:
 			;       Cycles              Accumulator         Carry flag
 			; 0  1  2  3  4  5  6          (hex)           0 1 2 3 4 5 6
 
@@ -23,3 +24,7 @@ dly2:	bne	dly3	; 2  2              3   00 00             01   0 1         0
 dly3:	rts		; 6  6  6  6  6  6  6   00 00 00 00 01 01 01   0 1 1 1 0 0 1
 	;
 	; Total cycles:	 25 26 27 28 29 30 31
+
+delay_end:
+
+.assert         >delay_begin = >delay_end, error, "delay_a crosses page"
diff --git a/xmas_2018/gr_fast_clear.s b/xmas_2018/gr_fast_clear.s
index 796b985a..9b1d73ff 100644
--- a/xmas_2018/gr_fast_clear.s
+++ b/xmas_2018/gr_fast_clear.s
@@ -91,7 +91,9 @@ no_draw_bottom:
 	bpl	clear_top_fast_loop					; 2nt/3
 
 	rts								; 6
+clear_top_end:
 
+.assert         >clear_top = >clear_top_end, error, "clear_top crosses page"
 
 
 
diff --git a/xmas_2018/gr_putsprite.s b/xmas_2018/gr_putsprite.s
index 2b54c6e1..18bb37cb 100644
--- a/xmas_2018/gr_putsprite.s
+++ b/xmas_2018/gr_putsprite.s
@@ -69,4 +69,6 @@ put_sprite_pixel:
 									; -1
 	rts				; return			; 6
 
+put_sprite_end:
 
+.assert         >put_sprite_no_transparency = >put_sprite_end, error, "put_sprite crosses page"
diff --git a/xmas_2018/gr_scroll.s b/xmas_2018/gr_scroll.s
index 3b78fb6b..f167a022 100644
--- a/xmas_2018/gr_scroll.s
+++ b/xmas_2018/gr_scroll.s
@@ -63,3 +63,5 @@ no_wrap:
 done_wrap:
 	rts							; 6
 
+
+.assert         >scroll_loop = >done_wrap, error, "gr_scroll crosses page"
diff --git a/xmas_2018/play_music.s b/xmas_2018/play_music.s
index df7c1f10..8b2b2093 100644
--- a/xmas_2018/play_music.s
+++ b/xmas_2018/play_music.s
@@ -242,9 +242,13 @@ mb_done_change:
 	rts			; 6
 				;=======
 				; 21
+play_music_end:
+
+.assert         >play_music = >play_music_end, error, "play_music crosses page"
 
 .align $100
-.include "mockingboard.s"
+
+pattern_begin:
 
 ; patterns 8 long
 mal_pattern:
@@ -264,6 +268,6 @@ mnl_pattern:
 mnh_pattern:
 .byte   >mnh00,>mnh01,>mnh02,>mnh03,>mnh04,>mnh05,>mnh06,>mnh07
 
+pattern_end:
 
-
-
+.assert         >pattern_begin = >pattern_end, error, "pattern crosses page"
diff --git a/xmas_2018/vapor_lock.s b/xmas_2018/vapor_lock.s
index fb9ceb3b..e965999a 100644
--- a/xmas_2018/vapor_lock.s
+++ b/xmas_2018/vapor_lock.s
@@ -238,3 +238,6 @@ done_vapor_lock:
 	;		language on the Apple II computer.
 	;	Cavanagh and Anstis: Visual psychophysics on the
 	;		Apple II: Getting started
+
+.assert         >vapor_lock_loop = >done_vapor_lock, error, "vapor_lock crosses page"
+
diff --git a/xmas_2018/xmas2018.s b/xmas_2018/xmas2018.s
index 39949706..242cddf1 100644
--- a/xmas_2018/xmas2018.s
+++ b/xmas_2018/xmas2018.s
@@ -180,20 +180,27 @@ game_over_man:
 .align $100
 	.include	"wreath.s"
 	.include	"ball.s"
-	.include	"gr_offsets.s"
-	.include	"gr_hline.s"
-	.include	"gr_fast_clear.s"
-	.include	"vapor_lock.s"
 	.include	"gr_putsprite.s"
-	.include	"delay_a.s"
+	.include	"gr_offsets.s"
+	.include	"vapor_lock.s"
+	.include	"gr_fast_clear.s"
 	.include	"play_music.s"
+	.include	"delay_a.s"
+	.include	"gr_scroll.s"
+	.include	"mockingboard.s"
+
 
 ; Things here alignment doesn't matter
+	.include	"gr_hline.s"
 	.include	"wait_keypress.s"
 	.include	"merry.s"
 	.include	"lz4_decode.s"
 	.include	"rts.s"
 
+greets:
+.incbin "greets.raw.lz4t"
+greets_end:
+
 ; filename to open is 30-character Apple text:
 wreath_filename:	; .byte "WREATH.LZ4",0
 	.byte 'W'|$80,'R'|$80,'E'|$80,'A'|$80,'T'|$80,'H'|$80,'.'|$80,'L'|$80