diff --git a/src/serpent.lua b/src/serpent.lua
index bbcf15f..af2e0d2 100644
--- a/src/serpent.lua
+++ b/src/serpent.lua
@@ -1,4 +1,4 @@
-local n, v = "serpent", 0.224 -- (C) 2012-13 Paul Kulchenko; MIT License
+local n, v = "serpent", 0.225 -- (C) 2012-13 Paul Kulchenko; MIT License
 local c, d = "Paul Kulchenko", "Lua serializer and pretty printer"
 local snum = {[tostring(1/0)]='1/0 --[[math.huge]]',[tostring(-1/0)]='-1/0 --[[-math.huge]]',[tostring(0/0)]='0/0'}
 local badtype = {thread = true, userdata = true}
@@ -95,7 +95,8 @@ local function s(t, opts)
   local sepr = indent and "\n" or ";"..space
   local body = val2str(t, name, indent) -- this call also populates sref
   local tail = #sref>1 and table.concat(sref, sepr)..sepr or ''
-  return not name and body or "do local "..body..sepr..tail.."return "..name..sepr.."end"
+  local warn = opts.comment and #sref>1 and space.."--[[incomplete output with shared/self-references skipped]]" or ''
+  return not name and body..warn or "do local "..body..sepr..tail.."return "..name..sepr.."end"
 end
 
 local function merge(a, b) if b then for k,v in pairs(b) do a[k] = v end end; return a; end