diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 6bf607302c..3ad2da88d1 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -2621,7 +2621,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	one dot may appear.
 	This option is not copied to another buffer, independent of the 's' or
 	'S' flag in 'cpoptions'.
-	Only alphanumeric characters, '-' and '_' can be used.
+	Only alphanumeric characters, '-' and '_' can be used (and a '.' is
+	allowed as delimiter when combining different filetypes).
 
 						*'fillchars'* *'fcs'*
 'fillchars' 'fcs'	string	(default "")
diff --git a/runtime/lua/vim/_meta/options.lua b/runtime/lua/vim/_meta/options.lua
index 90118cb4a1..3380f90ce2 100644
--- a/runtime/lua/vim/_meta/options.lua
+++ b/runtime/lua/vim/_meta/options.lua
@@ -2313,7 +2313,8 @@ vim.go.fic = vim.go.fileignorecase
 --- one dot may appear.
 --- This option is not copied to another buffer, independent of the 's' or
 --- 'S' flag in 'cpoptions'.
---- Only alphanumeric characters, '-' and '_' can be used.
+--- Only alphanumeric characters, '-' and '_' can be used (and a '.' is
+--- allowed as delimiter when combining different filetypes).
 ---
 --- @type string
 vim.o.filetype = ""
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index 75c6f51fae..fa92b1481d 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -3030,7 +3030,8 @@ local options = {
         one dot may appear.
         This option is not copied to another buffer, independent of the 's' or
         'S' flag in 'cpoptions'.
-        Only alphanumeric characters, '-' and '_' can be used.
+        Only alphanumeric characters, '-' and '_' can be used (and a '.' is
+        allowed as delimiter when combining different filetypes).
       ]=],
       full_name = 'filetype',
       noglob = true,