diff --git a/pages/2018-08-27-YAML-For-Nonprogrammers.md b/pages/2018-08-27-YAML-For-Nonprogrammers.md
index 7c66289..3125f01 100644
--- a/pages/2018-08-27-YAML-For-Nonprogrammers.md
+++ b/pages/2018-08-27-YAML-For-Nonprogrammers.md
@@ -253,6 +253,7 @@ Children:
 
 Things to note:
 
+- The space after the comma is important.
 - The value of `Hobbies` is a list. Like above, each line of the value is
   indented by an equal number of spaces.
 - The value of `Phones` is a dictionary. The same indentation rules apply.