diff --git a/src/chapter-29.md b/src/chapter-29.md
index 6f095cb..45f7c3f 100644
--- a/src/chapter-29.md
+++ b/src/chapter-29.md
@@ -820,7 +820,7 @@ WAIT_KEY macro
               endm
 ;
 stack         segment para stack ‘STACK'
-              db512 dup (?)
+              db 512 dup (?)
 stack         ends
 ;
 Data  segment   word   ‘DATA'