diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index 7d6b92d..adc1d56 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -5368,7 +5368,9 @@
 							*hl-MatchParen*
 MatchParen	Character under the cursor or just before it, if it
 		is a paired bracket, and its match. |pi_paren.txt|
-
+							*hl-MessageWindow*
+MessageWindow	Messages popup window used when 'cmdheight' is zero.  If not
+		defined |hl-WarningMsg| is used.
 							*hl-ModeMsg*
 ModeMsg		'showmode' message (e.g., "-- INSERT --").
 							*hl-MoreMsg*
@@ -5388,6 +5390,10 @@
 PmenuSbar	Popup menu: Scrollbar.
 							*hl-PmenuThumb*
 PmenuThumb	Popup menu: Thumb of the scrollbar.
+							*hl-PopupNotification*
+PopupNotification
+		Popup window created with |popup_notification()|.  If not
+		defined |hl-WarningMsg| is used.
 							*hl-Question*
 Question	|hit-enter| prompt and yes/no questions.
 							*hl-QuickFixLine*