diff --git a/omemo/modules/omemo.py b/omemo/modules/omemo.py
index b0a01aa..7e5b7eb 100644
--- a/omemo/modules/omemo.py
+++ b/omemo/modules/omemo.py
@@ -310,20 +310,12 @@ class OMEMO(BaseModule):
         else:
             self.backend.add_muc_member(room, jid)
 
-        if room in self._omemo_groupchats:
+        if self.is_omemo_groupchat(room):
             if not self.is_contact_in_roster(jid):
                 # Query Devicelists from JIDs not in our Roster
                 self._log.info('%s not in Roster, query devicelist...', jid)
                 self.request_devicelist(jid)
 
-        if properties.is_muc_self_presence:
-            if StatusCode.NON_ANONYMOUS in status_codes:
-                # non-anonymous Room (Full JID)
-                self._omemo_groupchats.add(room)
-
-                self._log.info('OMEMO capable Room found: %s', room)
-                self.get_affiliation_list(room)
-
     def get_affiliation_list(self, room_jid):
         for affiliation in ('owner', 'admin', 'member'):
             self._nbxmpp('MUC').get_affiliation(
@@ -354,11 +346,22 @@ class OMEMO(BaseModule):
             return False
         return contact.sub == 'both'
 
-    def on_muc_config_changed(self, event):
-        status_codes = event.status_codes or []
-        if StatusCode.CONFIG_NON_ANONYMOUS in status_codes:
-            self._omemo_groupchats.add(event.room_jid)
-            self._log.info('Room config change: non-anonymous')
+    def on_muc_disco_update(self, event):
+        self._check_if_omemo_capable(event.room_jid)
+
+    def on_muc_joined(self, event):
+        self._check_if_omemo_capable(event.room_jid)
+        if self.is_omemo_groupchat(event.room_jid):
+            self.get_affiliation_list(event.room_jid)
+
+    def _check_if_omemo_capable(self, jid):
+        disco_info = app.logger.get_last_disco_info(jid)
+        if disco_info.muc_is_members_only and disco_info.muc_is_nonanonymous:
+            self._log.info('OMEMO room discovered: %s', jid)
+            self._omemo_groupchats.add(jid)
+        else:
+            self._log.info('OMEMO room removed due to config change: %s', jid)
+            self._omemo_groupchats.discard(jid)
 
     def _check_for_missing_sessions(self, jid):
         devices_without_session = self.backend.devices_without_sessions(jid)
diff --git a/omemo/plugin.py b/omemo/plugin.py
index b054863..dad325c 100644
--- a/omemo/plugin.py
+++ b/omemo/plugin.py
@@ -91,7 +91,8 @@ class OmemoPlugin(GajimPlugin):
         self.events_handlers = {
             'omemo-new-fingerprint': (ged.PRECORE, self._on_new_fingerprints),
             'signed-in': (ged.PRECORE, self._on_signed_in),
-            'muc-config-changed': (ged.GUI2, self._on_muc_config_changed),
+            'muc-disco-update': (ged.GUI1, self._on_muc_disco_update),
+            'muc-joined': (ged.GUI1, self._on_muc_joined),
         }
         self.modules = [omemo]
         self.config_dialog = OMEMOConfigDialog(self)
@@ -177,10 +178,15 @@ class OmemoPlugin(GajimPlugin):
             return
         self.get_omemo(account).on_signed_in()
 
-    def _on_muc_config_changed(self, event):
+    def _on_muc_disco_update(self, event):
         if not self._is_enabled_account(event.account):
             return
-        self.get_omemo(event.account).on_muc_config_changed(event)
+        self.get_omemo(event.account).on_muc_disco_update(event)
+
+    def _on_muc_joined(self, event):
+        if not self._is_enabled_account(event.account):
+            return
+        self.get_omemo(event.account).on_muc_joined(event)
 
     def _update_caps(self, account):
         if not self._is_enabled_account(account):
@@ -189,14 +195,6 @@ class OmemoPlugin(GajimPlugin):
 
     @staticmethod
     def activate_encryption(chat_control):
-        if isinstance(chat_control, GroupchatControl):
-            omemo_con = app.connections[chat_control.account].get_module('OMEMO')
-            if not omemo_con.is_omemo_groupchat(chat_control.room_jid):
-                dialogs.ErrorDialog(
-                    _('Bad Configuration'),
-                    _('To use OMEMO in a Groupchat, the Groupchat should be'
-                      ' non-anonymous and members-only.'))
-                return False
         return True
 
     def _muc_encrypt_message(self, conn, obj, callback):
@@ -249,6 +247,14 @@ class OmemoPlugin(GajimPlugin):
         self.new_fingerprints_available(chat_control)
         if isinstance(chat_control, GroupchatControl):
             room = chat_control.room_jid
+            if not omemo.is_omemo_groupchat(room):
+                dialogs.ErrorDialog(
+                    _('Bad Configuration'),
+                    _('To use OMEMO in a Groupchat, the Groupchat should be'
+                      ' non-anonymous and members-only.'))
+                chat_control.sendmessage = False
+                return
+
             missing = True
             for jid in omemo.backend.get_muc_members(room):
                 if not omemo.are_keys_missing(jid):
@@ -257,6 +263,7 @@ class OmemoPlugin(GajimPlugin):
                 log.info('%s => No Trusted Fingerprints for %s',
                          account, room)
                 self.print_message(chat_control, UserMessages.NO_FINGERPRINTS)
+                chat_control.sendmessage = False
         else:
             # check if we have devices for the contact
             if not omemo.backend.get_devices(contact.jid, without_self=True):