diff --git a/runtime/autoload/dist/ft.vim b/runtime/autoload/dist/ft.vim
index 0c0b872..95135c8 100644
--- a/runtime/autoload/dist/ft.vim
+++ b/runtime/autoload/dist/ft.vim
@@ -3,7 +3,7 @@
 # Vim functions for file type detection
 #
 # Maintainer:		The Vim Project <https://github.com/vim/vim>
-# Last Change:		2025 Apr 19
+# Last Change:		2025 Apr 21
 # Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 # These functions are moved here from runtime/filetype.vim to make startup
@@ -639,13 +639,14 @@
   setf mmix
 enddef
 
-# This function checks if one of the first five lines start with a dot.  In
-# that case it is probably an nroff file: 'filetype' is set and 1 is returned.
+# This function checks if one of the first five lines start with a typical
+# nroff pattern in man files.  In that case it is probably an nroff file:
+# 'filetype' is set and 1 is returned.
 export def FTnroff(): number
   var n = 1
-  while n < 5
+  while n <= 5
     var line = getline(n)
-    if line =~ '^\.\S\S\?'
+    if line =~ '^\%([.'']\s*\%(TH\|D[dt]\|S[Hh]\|d[es]1\?\|so\)\s\+\S\|[.'']\s*ig\>\|\%([.'']\s*\)\?\\"\)'
       setf nroff
       return 1
     endif
diff --git a/runtime/filetype.vim b/runtime/filetype.vim
index da74e25..98e64a9 100644
--- a/runtime/filetype.vim
+++ b/runtime/filetype.vim
@@ -1,7 +1,7 @@
 " Vim support file to detect file types
 "
 " Maintainer:	The Vim Project <https://github.com/vim/vim>
-" Last Change:	2025 Apr 19
+" Last Change:	2025 Apr 21
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " Listen very carefully, I will say this only once
@@ -1728,7 +1728,7 @@
 	\   setf nroff |
 	\ endif
 au BufNewFile,BufRead *.tr,*.nr,*.roff,*.tmac,*.mom	setf nroff
-au BufNewFile,BufRead *.[0-9],*.[013]p,*.[1-8]x,*.3{am,perl,pm,posix,type},*.[nlop]	call dist#ft#FTnroff()
+au BufNewFile,BufRead *.[0-9],*.[013]p,*.[1-8]x,*.3{am,perl,pm,posix,type},*.n	call dist#ft#FTnroff()
 
 " Nroff or Objective C++
 au BufNewFile,BufRead *.mm			call dist#ft#FTmm()