--- a/runtime/ftplugin/erlang.vim
+++ b/runtime/ftplugin/erlang.vim
@@ -1,87 +1,83 @@
 " Vim ftplugin file
-" Language:     Erlang
+" Language:     Erlang (http://www.erlang.org)
+" Maintainer:   Csaba Hoch <csaba.hoch@gmail.com>
 " Author:       Oscar Hellström <oscar@oscarh.net>
 " Contributors: Ricardo Catalinas Jiménez <jimenezrick@gmail.com>
 "               Eduardo Lopez (http://github.com/tapichu)
+"               Arvid Bjurklint (http://github.com/slarwise)
+" Last Update:  2021-Jan-08
 " License:      Vim license
-" Version:      2012/01/25
+" URL:          https://github.com/vim-erlang/vim-erlang-runtime
 
 if exists('b:did_ftplugin')
-	finish
-else
-	let b:did_ftplugin = 1
+  finish
 endif
-
-if exists('s:did_function_definitions')
-	call s:SetErlangOptions()
-	finish
-else
-	let s:did_function_definitions = 1
-endif
+let b:did_ftplugin = 1
 
 let s:cpo_save = &cpo
 set cpo&vim
 
-if !exists('g:erlang_keywordprg')
-	let g:erlang_keywordprg = 'erl -man'
+let &l:keywordprg = get(g:, 'erlang_keywordprg', 'erl -man')
+
+if get(g:, 'erlang_folding', 0)
+  setlocal foldmethod=expr
+  setlocal foldexpr=GetErlangFold(v:lnum)
+  setlocal foldtext=ErlangFoldText()
 endif
 
-if !exists('g:erlang_folding')
-	let g:erlang_folding = 0
-endif
+setlocal comments=:%%%,:%%,:%
+setlocal commentstring=%%s
+
+setlocal formatoptions+=ro
+
+setlocal suffixesadd=.erl,.hrl
+
+let &l:include = '^\s*-\%(include\|include_lib\)\s*("\zs\f*\ze")'
+let &l:define  = '^\s*-\%(define\|record\|type\|opaque\)'
 
 let s:erlang_fun_begin = '^\a\w*(.*$'
 let s:erlang_fun_end   = '^[^%]*\.\s*\(%.*\)\?$'
 
-function s:SetErlangOptions()
-	if g:erlang_folding
-		setlocal foldmethod=expr
-		setlocal foldexpr=GetErlangFold(v:lnum)
-		setlocal foldtext=ErlangFoldText()
-	endif
-
-	setlocal comments=:%%%,:%%,:%
-	setlocal commentstring=%%s
+if !exists('*GetErlangFold')
+  function GetErlangFold(lnum)
+    let lnum = a:lnum
+    let line = getline(lnum)
 
-	setlocal formatoptions+=ro
-	let &l:keywordprg = g:erlang_keywordprg
-endfunction
+    if line =~ s:erlang_fun_end
+      return '<1'
+    endif
 
-function GetErlangFold(lnum)
-	let lnum = a:lnum
-	let line = getline(lnum)
+    if line =~ s:erlang_fun_begin && foldlevel(lnum - 1) == 1
+      return '1'
+    endif
 
-	if line =~ s:erlang_fun_end
-		return '<1'
-	endif
+    if line =~ s:erlang_fun_begin
+      return '>1'
+    endif
 
-	if line =~ s:erlang_fun_begin && foldlevel(lnum - 1) == 1
-		return '1'
-	endif
-
-	if line =~ s:erlang_fun_begin
-		return '>1'
-	endif
-
-	return '='
-endfunction
+    return '='
+  endfunction
+endif
 
-function ErlangFoldText()
-	let line    = getline(v:foldstart)
-	let foldlen = v:foldend - v:foldstart + 1
-	let lines   = ' ' . foldlen . ' lines: ' . substitute(line, "[\ \t]*", '', '')
-	if foldlen < 10
-		let lines = ' ' . lines
-	endif
-	let retval = '+' . v:folddashes . lines
+if !exists('*ErlangFoldText')
+  function ErlangFoldText()
+    let line    = getline(v:foldstart)
+    let foldlen = v:foldend - v:foldstart + 1
+    let lines   = ' ' . foldlen . ' lines: ' . substitute(line, "[\ \t]*", '', '')
+    if foldlen < 10
+      let lines = ' ' . lines
+    endif
+    let retval = '+' . v:folddashes . lines
 
-	return retval
-endfunction
+    return retval
+  endfunction
+endif
 
-call s:SetErlangOptions()
-
-let b:undo_ftplugin = "setlocal foldmethod< foldexpr< foldtext<"
-	\ . " comments< commentstring< formatoptions<"
+let b:undo_ftplugin = "setlocal keywordprg< foldmethod< foldexpr< foldtext<"
+      \ . " comments< commentstring< formatoptions< suffixesadd< include<"
+      \ . " define<"
 
 let &cpo = s:cpo_save
 unlet s:cpo_save
+
+" vim: sw=2 et