diff --git a/runtime/ftplugin/systemd.vim b/runtime/ftplugin/systemd.vim
index 4c5c9a1..c0bc630 100644
--- a/runtime/ftplugin/systemd.vim
+++ b/runtime/ftplugin/systemd.vim
@@ -7,35 +7,30 @@
   runtime! ftplugin/dosini.vim
 endif
 
-if !has('unix')
-  finish
-endif
-
-if !has('gui_running')
-  command! -buffer -nargs=1 Sman silent exe '!' . KeywordLookup_systemd(<q-args>) | redraw!
-elseif has('terminal')
-  command! -buffer -nargs=1 Sman silent exe 'term ' . KeywordLookup_systemd(<q-args>)
-else
-  finish
-endif
-
-if !exists('*KeywordLookup_systemd')
-  function KeywordLookup_systemd(keyword) abort
-    let matches = matchlist(getline(search('\v^\s*\[\s*.+\s*\]\s*$', 'nbWz')), '\v^\s*\[\s*(\k+).*\]\s*$')
-    if len(matches) > 1
-      let section = matches[1]
-      return 'LESS= MANPAGER="less --pattern=''(^|,)\s+' . a:keyword . '=$'' --hilite-search" man ' . 'systemd.' . section
-    else
-      return 'LESS= MANPAGER="less --pattern=''(^|,)\s+' . a:keyword . '=$'' --hilite-search" man ' . 'systemd'
+if has('unix') && executable('less')
+  if !has('gui_running')
+    command -buffer -nargs=1 Sman silent exe '!' . KeywordLookup_systemd(<q-args>) | redraw!
+  elseif has('terminal')
+    command -buffer -nargs=1 Sman silent exe 'term ' . KeywordLookup_systemd(<q-args>)
+  endif
+  if exists(':Sman') == 2
+    if !exists('*KeywordLookup_systemd')
+      function KeywordLookup_systemd(keyword) abort
+        let matches = matchlist(getline(search('\v^\s*\[\s*.+\s*\]\s*$', 'nbWz')), '\v^\s*\[\s*(\k+).*\]\s*$')
+        if len(matches) > 1
+          let section = matches[1]
+          return 'LESS= MANPAGER="less --pattern=''(^|,)\s+' . a:keyword . '=$'' --hilite-search" man ' . 'systemd.' . section
+        else
+          return 'LESS= MANPAGER="less --pattern=''(^|,)\s+' . a:keyword . '=$'' --hilite-search" man ' . 'systemd'
+        endif
+      endfunction
     endif
-  endfunction
-endif
-
-setlocal iskeyword+=-
-setlocal keywordprg=:Sman
-
-if !exists('b:undo_ftplugin') || empty(b:undo_ftplugin)
-  let b:undo_ftplugin = 'setlocal keywordprg< iskeyword<'
-else
-  let b:undo_ftplugin .= '| setlocal keywordprg< iskeyword<'
+    setlocal iskeyword+=-
+    setlocal keywordprg=:Sman
+    if !exists('b:undo_ftplugin') || empty(b:undo_ftplugin)
+      let b:undo_ftplugin = 'setlocal keywordprg< iskeyword<'
+    else
+      let b:undo_ftplugin .= '| setlocal keywordprg< iskeyword<'
+    endif
+  endif
 endif