diff --git a/docs/reference/migration/migrate_2_0/mapping.asciidoc b/docs/reference/migration/migrate_2_0/mapping.asciidoc
index edeb243a9ca..de0f899fcc5 100644
--- a/docs/reference/migration/migrate_2_0/mapping.asciidoc
+++ b/docs/reference/migration/migrate_2_0/mapping.asciidoc
@@ -164,6 +164,12 @@ fields in differnt types, this warning has been relaxed: type names may now
 contain dots, but they may not *begin* with a dot.  The only exception to this
 is the special `.percolator` type.
 
+==== Type names may not be longer than 255 characters
+
+Mapping type names may not be longer than 255 characters.  Long type names
+will continue to function on indices created before upgrade, but it will not
+be possible create types with long names in new indices.
+
 ==== Types may no longer be deleted
 
 In 1.x it was possible to delete a type mapping, along with all of the
@@ -395,4 +401,4 @@ The default `position_increment_gap` is now 100. Indexes created in Elasticsearc
 to use the old default of 0. This was done to prevent phrase queries from
 matching across different values of the same term unexpectedly. Specifically,
 100 was chosen to cause phrase queries with slops up to 99 to match only within
-a single value of a field.
\ No newline at end of file
+a single value of a field.