diff --git a/prosody-modules/mod_muc_poll/message.lib.lua b/prosody-modules/mod_muc_poll/message.lib.lua
index feb94b42..0a1b8850 100644
--- a/prosody-modules/mod_muc_poll/message.lib.lua
+++ b/prosody-modules/mod_muc_poll/message.lib.lua
@@ -3,10 +3,18 @@
 
 local id = require "util.id";
 local st = require "util.stanza";
-local format = require"util.format".format;
+local timer = require "util.timer";
 local xmlns_occupant_id = "urn:xmpp:occupant-id:0";
+local xmlns_replace = "urn:xmpp:message-correct:0";
 
-local function build_poll_message(room, message_id)
+local mod_muc = module:depends"muc";
+local get_room_from_jid = mod_muc.get_room_from_jid;
+
+local debounce_delay = 10; -- number of seconds during which we must group votes to avoid flood.
+local scheduled_updates = {};
+
+-- construct the poll message stanza
+local function build_poll_message(room, message_id, is_end_message)
   local current_poll = room._data.current_poll;
   if not current_poll then
     return nil;
@@ -15,6 +23,10 @@ local function build_poll_message(room, message_id)
 
   local content = current_poll["muc#roompoll_question"] .. "\n";
 
+  if is_end_message then
+    content = content .. "This poll is now over.\n";
+  end
+
   local total = 0;
   for choice, nb in pairs(current_poll.votes_by_choices) do
     total = total + nb;
@@ -23,12 +35,15 @@ local function build_poll_message(room, message_id)
     content = content .. choice .. ': ' .. label;
     if total > 0 then
       local nb = current_poll.votes_by_choices[choice] or 0;
-      local percent = format("%d.%d%d", nb * 100 / total);
+      local percent = string.format("%.2f", nb * 100 / total);
       content = content .. " (" .. nb .. "/" .. total .. " = " .. percent .. "%)";
     end
     content = content .. "\n";
   end
-  content = content .. "Send a message with an exclamation mark followed by your choice number to vote. Example: !1\n";
+
+  if not is_end_message then
+    content = content .. "Send a message with an exclamation mark followed by your choice number to vote. Example: !1\n";
+  end
 
   local msg = st.message({
     type = "groupchat",
@@ -44,32 +59,67 @@ local function build_poll_message(room, message_id)
   return msg;
 end
 
+-- sends a message when the poll starts.
 local function poll_start_message(room)
   if not room._data.current_poll then
     return nil;
   end
   module:log("debug", "Sending the start message for room %s poll", room.jid);
   local message_id = id.medium();
-  local msg = build_poll_message(room, message_id);
+  local msg = build_poll_message(room, message_id, false);
   room:broadcast_message(msg);
   return message_id;
 end
 
-local function schedule_poll_update_message(room)
-  -- TODO
+-- Send the poll update message
+local function send_poll_update_message(room)
+  if not room._data.current_poll then
+    return nil;
+  end
+  module:log("debug", "Sending an update message for room %s poll", room.jid);
+  local message_id = id.medium(); -- generate a new id
+  local msg = build_poll_message(room, message_id, false);
 
-  -- if not room._data.current_poll then
-  --   return nil;
-  -- end
-  -- module:log("debug", "Sending an update message for room %s poll", room.jid);
-  -- local message_id = id.medium();
-  -- local msg = build_poll_message(room, message_id);
-  -- room:broadcast_message(msg);
-  -- return message_id;
+  -- the update message is a <replace> message (see XEP-0308).
+  msg:tag('replace', {
+    xmlns = xmlns_replace;
+    id = room._data.current_poll.start_message_id;
+  }):up();
+
+  room:broadcast_message(msg);
+  return message_id;
 end
 
+-- Schedule an update of the start message.
+-- We do not send this update each time someone vote,
+-- to avoid flooding.
+local function schedule_poll_update_message(room_jid)
+  if scheduled_updates[room_jid] then
+    -- already a running timer, we can ignore to debounce.
+    return;
+  end
+  scheduled_updates[room_jid] = timer.add_task(debounce_delay, function()
+    scheduled_updates[room_jid] = nil;
+    -- We dont pass room, because here it could have been removed from memory.
+    -- So we must relad the room from the JID in any case.
+    local room = get_room_from_jid(room_jid);
+    if not room then
+      return;
+    end
+    send_poll_update_message(room);
+  end);
+end
+
+-- Send a new message when the poll is over, with the result.
 local function poll_end_message(room)
-  -- TODO
+  if not room._data.current_poll then
+    return nil;
+  end
+  module:log("debug", "Sending the end message for room %s poll", room.jid);
+  local message_id = id.medium(); -- generate a new id
+  local msg = build_poll_message(room, message_id, true);
+  room:broadcast_message(msg);
+  return message_id;
 end
 
 return {
diff --git a/prosody-modules/mod_muc_poll/poll.lib.lua b/prosody-modules/mod_muc_poll/poll.lib.lua
index 6d15a8bd..3af17acd 100644
--- a/prosody-modules/mod_muc_poll/poll.lib.lua
+++ b/prosody-modules/mod_muc_poll/poll.lib.lua
@@ -56,7 +56,9 @@ local function end_current_poll (room)
     timer.stop(scheduled_end[room_jid]);
     scheduled_end[room_jid] = nil;
   end
+
   poll_end_message(room);
+
   -- TODO: store the result somewhere, to keep track?
 
   -- We don't remove the poll immediatly. Indeed, if the vote is anonymous,
@@ -173,18 +175,18 @@ local function handle_groupchat(event)
   module:log("debug", "Counting a new vote for room %s: choice %i, voter %s", room.jid, choice, occupant_bare_id);
   -- counting the vote:
   if room._data.current_poll.votes_by_occupant[occupant_bare_id] ~= nil then
-    module:log("debug", "Occupant %s has already voted for current room %s vote, reassigning his vote.", occupant_bare_id);
+    module:log("debug", "Occupant %s has already voted for current room %s vote, reassigning his vote.", occupant_bare_id, room.jid);
     room._data.current_poll.votes_by_choices[room._data.current_poll.votes_by_occupant[occupant_bare_id]] = room._data.current_poll.votes_by_choices[room._data.current_poll.votes_by_occupant[occupant_bare_id]] - 1;
   end
   room._data.current_poll.votes_by_choices[choice] = room._data.current_poll.votes_by_choices[choice] + 1;
   room._data.current_poll.votes_by_occupant[occupant_bare_id] = choice;
 
-  schedule_poll_update_message(room);
+  schedule_poll_update_message(room.jid);
 
   -- When the poll is anonymous, we bounce the messages (but count the votes).
   local must_bounce = room._data.current_poll["muc#roompoll_anonymous"] == true;
   if must_bounce then
-    module:log("debug", "Invalid vote, bouncing it.");
+    module:log("debug", "Anonymous votes, bouncing it.");
     origin.send(st.error_reply(
       stanza,
       -- error_type
@@ -218,7 +220,7 @@ local function room_restored(event)
     schedule_poll_end(room.jid, room._data.current_poll.end_timestamp);
   end
   -- just in case, we can also reschedule an update message
-  schedule_poll_update_message(room);
+  schedule_poll_update_message(room.jid);
 end
 
 return {