diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 7848534..d31ba2d 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -2524,6 +2524,9 @@
 expandcmd({expr})		String	expand {expr} like with `:edit`
 extend({expr1}, {expr2} [, {expr3}])
 				List/Dict insert items of {expr2} into {expr1}
+extendnew({expr1}, {expr2} [, {expr3}])
+				List/Dict like |extend()| but creates a new
+					List or Dictionary
 feedkeys({string} [, {mode}])	Number	add key sequence to typeahead buffer
 filereadable({file})		Number	|TRUE| if {file} is a readable file
 filewritable({file})		Number	|TRUE| if {file} is a writable file
@@ -4520,6 +4523,13 @@
 			mylist->extend(otherlist)
 
 
+extendnew({expr1}, {expr2} [, {expr3}])			*extendnew()*
+		Like |extend()| but instead of adding items to {expr1} a new
+		List or Dictionary is created and returned.  {expr1} remains
+		unchanged.  Items can still be changed by {expr2}, if you
+		don't want that use |deepcopy()| first.
+
+
 feedkeys({string} [, {mode}])				*feedkeys()*
 		Characters in {string} are queued for processing as if they
 		come from a mapping or were typed by the user.
diff --git a/runtime/doc/usr_41.txt b/runtime/doc/usr_41.txt
index 7d4e3a2..624bb93 100644
--- a/runtime/doc/usr_41.txt
+++ b/runtime/doc/usr_41.txt
@@ -640,6 +640,7 @@
 	insert()		insert an item somewhere in a List
 	add()			append an item to a List
 	extend()		append a List to a List
+	extendnew()		make a new List and append items
 	remove()		remove one or more items from a List
 	copy()			make a shallow copy of a List
 	deepcopy()		make a full copy of a List
@@ -669,6 +670,7 @@
 	empty()			check if Dictionary is empty
 	remove()		remove an entry from a Dictionary
 	extend()		add entries from one Dictionary to another
+	extendnew()		make a new Dictionary and append items
 	filter()		remove selected entries from a Dictionary
 	map()			change each Dictionary entry
 	mapnew()		make a new Dictionary with changed items