diff --git a/runtime/optwin.vim b/runtime/optwin.vim
index b1d303009a..1742c64c3e 100644
--- a/runtime/optwin.vim
+++ b/runtime/optwin.vim
@@ -765,8 +765,10 @@ if has("insert_expand")
   call <SID>OptionG("cot", &cot)
   call append("$", "pumheight\tmaximum height of the popup menu")
   call <SID>OptionG("ph", &ph)
-  call append("$", "pumwidth\tminimum width of the popup menu")
-  call <SID>OptionG("pw", &pw)
+  if exists("&pw")
+    call append("$", "pumwidth\tminimum width of the popup menu")
+    call <SID>OptionG("pw", &pw)
+  endif
   call append("$", "completefunc\tuser defined function for Insert mode completion")
   call append("$", "\t(local to buffer)")
   call <SID>OptionL("cfu")