diff --git a/CHANGELOG.md b/CHANGELOG.md
index d1782572..b75cdbaf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 
 * Builtin prosody use a working dir provided by Peertube (needs Peertube >= 3.2.0)
 * Starting with Peertube 3.2.0, builtin prosody save room history on server. So when a user connects, he can get previously send messages.
+* Starting with Peertube 3.2.0, builtin prosody also activate mod_muc_moderation, enabling moderators to moderate messages. NB: unfortunately it requires Prosody>=0.11.8, which is not released yet (ability to change overwrite old messages on internal storages).
 
 ### Fixes
 
diff --git a/ROADMAP.md b/ROADMAP.md
index e4ab2204..4cb4a143 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -18,7 +18,7 @@ This roadmap is given as an indication. It will be updated as we go along accord
 [ ] | [ ] | Builtin Prosody | Check with yunohost how to integrate.
 [ ] | [ ] | Documentation | Rewrite documentation for more clarity. Add screenshots. Separate user and admin documentation.
 [ ] | [ ] | ConverseJS | UI: make custom templates, for a better UI/UX. Autoshow muc participants depending on the chat window width.
-[ ] | [ ] | Builtin Prosody | Allow moderators to delete messages (mod_muc_moderation)
+[x] | [ ] | Builtin Prosody | Allow moderators to delete messages (mod_muc_moderation). NB: Prosody dont allow it for now on «internal» storage, will be available in next version (0.11.8?). | Not Released yet
 [ ] | [ ] | ConverseJS | For anonymous user, automatically log in with a random nickname (and allow to change afterward)
 [ ] | [x] | JS | Modernise code to use new placeholders provided by Peertube 3.2.0 (with or without backward compatibility)
 [ ] | [x] | Settings | Replace some checkbox by a select (for the webchat mode). Migrate old checkbox values.
diff --git a/prosody-modules/mod_muc_moderation/README.markdown b/prosody-modules/mod_muc_moderation/README.markdown
new file mode 100644
index 00000000..ef9e1c3a
--- /dev/null
+++ b/prosody-modules/mod_muc_moderation/README.markdown
@@ -0,0 +1,32 @@
+# Introduction
+
+This module implements [XEP-0425: Message Moderation].
+
+# Usage
+
+Moderation is done via a supporting client and requires a `moderator`
+role in the channel / group chat.
+
+# Configuration
+
+Example [MUC component][doc:chatrooms] configuration:
+
+``` {.lua}
+VirtualHost "channels.example.com" "muc"
+modules_enabled = {
+    "muc_mam",
+    "muc_moderation",
+}
+```
+
+# Compatibility
+
+-   Should work with Prosody 0.11.x and later.
+-   Tested with trunk rev `52c6dfa04dba`.
+-   Message tombstones requires a compatible storage module implementing
+    a new message replacement API.
+
+## Clients
+
+-   Tested with [Converse.js](https://conversejs.org/)
+    [v6.0.1](https://github.com/conversejs/converse.js/releases/tag/v6.0.1)
diff --git a/prosody-modules/mod_muc_moderation/mod_muc_moderation.lua b/prosody-modules/mod_muc_moderation/mod_muc_moderation.lua
new file mode 100644
index 00000000..41a57808
--- /dev/null
+++ b/prosody-modules/mod_muc_moderation/mod_muc_moderation.lua
@@ -0,0 +1,123 @@
+-- mod_muc_moderation
+--
+-- Copyright (C) 2015-2020 Kim Alvefur
+--
+-- This file is MIT licensed.
+--
+-- Implements: XEP-0425: Message Moderation
+--
+-- Imports
+local dt = require "util.datetime";
+local id = require "util.id";
+local jid = require "util.jid";
+local st = require "util.stanza";
+
+-- Plugin dependencies
+local mod_muc = module:depends "muc";
+
+local muc_util = module:require "muc/util";
+local valid_roles = muc_util.valid_roles;
+
+local muc_log_archive = module:open_store("muc_log", "archive");
+
+if not muc_log_archive.set then
+	module:log("warn", "Selected archive storage module does not support message replacement, no tombstones will be saved");
+end
+
+-- Namespaces
+local xmlns_fasten = "urn:xmpp:fasten:0";
+local xmlns_moderate = "urn:xmpp:message-moderate:0";
+local xmlns_retract = "urn:xmpp:message-retract:0";
+
+-- Discovering support
+module:hook("muc-disco#info", function (event)
+	event.reply:tag("feature", { var = xmlns_moderate }):up();
+end);
+
+-- Main handling
+module:hook("iq-set/bare/" .. xmlns_fasten .. ":apply-to", function (event)
+	local stanza, origin = event.stanza, event.origin;
+
+	-- Collect info we need
+	local apply_to = stanza.tags[1];
+	local moderate_tag = apply_to:get_child("moderate", xmlns_moderate);
+	if not moderate_tag then return end -- some other kind of fastening?
+
+	local reason = moderate_tag:get_child_text("reason");
+
+	local room_jid = stanza.attr.to;
+	local room_node = jid.split(room_jid);
+	local room = mod_muc.get_room_from_jid(room_jid);
+
+	local stanza_id = apply_to.attr.id;
+
+	-- Permissions
+	local actor = stanza.attr.from;
+	local actor_nick = room:get_occupant_jid(actor);
+	local affiliation = room:get_affiliation(actor);
+	local role = room:get_role(actor_nick) or room:get_default_role(affiliation);
+	if valid_roles[role or "none"] < valid_roles.moderator then
+		origin.send(st.error_reply(stanza, "auth", "forbidden", "You need a role of at least 'moderator'"));
+		return true;
+	end
+
+	-- Original stanza to base tombstone on
+	local original, err;
+	if muc_log_archive.get then
+		original, err = muc_log_archive:get(room_node, stanza_id);
+	else
+		-- COMPAT missing :get API
+		err = "item-not-found";
+		for i, item in muc_log_archive:find(room_node, { key = stanza_id, limit = 1 }) do
+			if i == stanza_id then
+				original, err = item, nil;
+			end
+		end
+	end
+	if not original then
+		if err == "item-not-found" then
+			origin.send(st.error_reply(stanza, "modify", "item-not-found"));
+		else
+			origin.send(st.error_reply(stanza, "wait", "internal-server-error"));
+		end
+		return true;
+	end
+
+	-- Replacements
+	local tombstone = st.message({ from = original.attr.from, type = "groupchat", id = original.attr.id })
+		:tag("moderated", { xmlns = xmlns_moderate, by = actor_nick })
+			:tag("retracted", { xmlns = xmlns_retract, stamp = dt.datetime() }):up();
+
+	local announcement = st.message({ from = room_jid, type = "groupchat", id = id.medium(), })
+		:tag("apply-to", { xmlns = xmlns_fasten, id = stanza_id })
+			:tag("moderated", { xmlns = xmlns_moderate, by = actor_nick })
+			:tag("retract", { xmlns = xmlns_retract }):up();
+
+	if reason then
+		tombstone:text_tag("reason", reason);
+		announcement:text_tag("reason", reason);
+	end
+
+	if muc_log_archive.set then
+		-- Tombstone
+		local was_replaced = muc_log_archive:set(room_node, stanza_id, tombstone);
+		if not was_replaced then
+			origin.send(st.error_reply(stanza, "wait", "internal-server-error"));
+			return true;
+		end
+	end
+
+	-- Done, tell people about it
+	module:log("info", "Message with id '%s' in room %s moderated by %s, reason: %s", stanza_id, room_jid, actor, reason);
+	room:broadcast_message(announcement);
+
+	origin.send(st.reply(stanza));
+	return true;
+end);
+
+module:hook("muc-message-is-historic", function (event)
+	-- Ensure moderation messages are stored
+	if event.stanza.attr.from == event.room.jid then
+		return event.stanza:get_child("apply-to", xmlns_fasten);
+	end
+end, 1);
diff --git a/server/lib/prosody/config/content.ts b/server/lib/prosody/config/content.ts
index f0c32101..7b18fb6c 100644
--- a/server/lib/prosody/config/content.ts
+++ b/server/lib/prosody/config/content.ts
@@ -120,6 +120,7 @@ class ProsodyConfigContent {
     this.global.set('pidfile', this.paths.pid)
     this.global.set('plugin_paths', [this.paths.modules])
     this.global.set('data_path', this.paths.data)
+    this.global.set('default_storage', 'internal')
     this.global.set('storage', 'internal')
 
     this.global.set('modules_enabled', [
@@ -222,6 +223,9 @@ class ProsodyConfigContent {
     this.muc.set('log_all_rooms', true)
     this.muc.set('muc_log_expires_after', duration)
     this.muc.set('muc_log_cleanup_interval', 4 * 60 * 60)
+
+    // We can also use mod_muc_moderation
+    this.muc.add('modules_enabled', 'muc_moderation')
   }
 
   setLog (level: ProsodyLogLevel, syslog?: ProsodyLogLevel[]): void {