diff --git a/dump.lua b/dump.lua
index 355bedc..670ad21 100644
--- a/dump.lua
+++ b/dump.lua
@@ -55,24 +55,22 @@ local function basic_dump(o)
 	--elseif tp == "function" then
 	--	return string.format("loadstring(%q)", string.dump(o))
     elseif tp == "userdata" then
-        if o:is_valid() then
-            if o.is_player then
-                if o:is_player() then
-                    return string.format('#<player: "%s">', o:get_player_name())
-                else
-                    local e = o:get_luaentity()
-                    if e then
-                        return string.format('#<luaentity: "%s">', e.name)
-                    else
-                        return string.format('#<ObjectRef: %s>', o)
-                    end
-                end
-            else
-                return tostring(o)
-            end
-        else
+        if o.is_valid and not o:is_valid() then
             return string.format('#<invalid_ref: %s>', o)
         end
+        if o.is_player then
+            if o:is_player() then
+                return string.format('#<player: "%s">', o:get_player_name())
+            else
+                local e = o:get_luaentity()
+                if e then
+                    return string.format('#<luaentity: "%s">', e.name)
+                else
+                    return string.format('#<ObjectRef: %s>', o)
+                end
+            end
+        end
+        return string.format("#<%s>", o)
     else
         return string.format("#<%s>", tp)
     end
diff --git a/init.lua b/init.lua
index 838d177..5f60fc6 100644
--- a/init.lua
+++ b/init.lua
@@ -75,7 +75,7 @@ local function create_shared_environment(player_name)
                         return magic()
                     elseif not g[key] then
                         core.chat_send_player(player_name, string.format("* Accessing undeclared variable: '%s'", key))
-                        g[key] = true
+                        g[key] = true -- warn only once
                     end
                 end
                 return res