diff --git a/lib/Chat/Parser/SystemMessage.php b/lib/Chat/Parser/SystemMessage.php
index fdd428b28c0..7c931003396 100644
--- a/lib/Chat/Parser/SystemMessage.php
+++ b/lib/Chat/Parser/SystemMessage.php
@@ -157,7 +157,13 @@ public function parseMessage(IComment $comment): array {
 		} else if ($message === 'user_added') {
 			$parsedParameters['user'] = $this->getUser($parameters['user']);
 			$parsedMessage = $this->l->t('{actor} added {user}');
-			if ($currentUserIsActor) {
+			if ($parsedParameters['user']['id'] === $parsedParameters['actor']['id']) {
+				if ($currentUserIsActor) {
+					$parsedMessage = $this->l->t('You joined the conversation');
+				} else {
+					$parsedMessage = $this->l->t('{actor} joined the conversation');
+				}
+			} else if ($currentUserIsActor) {
 				$parsedMessage = $this->l->t('You added {user}');
 			} else if ($this->recipient instanceof IUser && $this->recipient->getUID() === $parsedParameters['user']['id']) {
 				$parsedMessage = $this->l->t('{actor} added you');
@@ -165,7 +171,11 @@ public function parseMessage(IComment $comment): array {
 		} else if ($message === 'user_removed') {
 			$parsedParameters['user'] = $this->getUser($parameters['user']);
 			if ($parsedParameters['user']['id'] === $parsedParameters['actor']['id']) {
-				$parsedMessage = $this->l->t('{actor} left the conversation');
+				if ($currentUserIsActor) {
+					$parsedMessage = $this->l->t('You left the conversation');
+				} else {
+					$parsedMessage = $this->l->t('{actor} left the conversation');
+				}
 			} else {
 				$parsedMessage = $this->l->t('{actor} removed {user}');
 				if ($currentUserIsActor) {
diff --git a/lib/Chat/SystemMessage/Listener.php b/lib/Chat/SystemMessage/Listener.php
index 65da003545a..22a984e865f 100644
--- a/lib/Chat/SystemMessage/Listener.php
+++ b/lib/Chat/SystemMessage/Listener.php
@@ -116,7 +116,7 @@ public function register() {
 			/** @var Room $room */
 			$room = $event->getSubject();
 			foreach ($participants as $participant) {
-				if ($userId !== $participant['userId']) {
+				if ($room->getObjectType() === 'file' || $userId !== $participant['userId']) {
 					$this->sendSystemMessage($room, 'user_added', ['user' => $participant['userId']]);
 				}
 			}
diff --git a/lib/Controller/FilesController.php b/lib/Controller/FilesController.php
index a706b8404a0..2a06817335c 100644
--- a/lib/Controller/FilesController.php
+++ b/lib/Controller/FilesController.php
@@ -24,6 +24,7 @@
 
 namespace OCA\Spreed\Controller;
 
+use OCA\Spreed\Exceptions\ParticipantNotFoundException;
 use OCA\Spreed\Exceptions\RoomNotFoundException;
 use OCA\Spreed\Files\Util;
 use OCA\Spreed\Manager;
@@ -75,8 +76,10 @@ public function __construct(
 	 * If there is no room associated to the given file id a new room is
 	 * created; the new room is a public room associated with a "file" object
 	 * with the given file id. Unlike normal rooms in which the owner is the
-	 * user that created the room these are special rooms without owner or any
-	 * other persistent participant.
+	 * user that created the room these are special rooms without owner
+	 * (although self joined users become persistent participants automatically
+	 * when they join until they explicitly leave or no longer have access to
+	 * the file).
 	 *
 	 * In any case, to create or even get the token of the room, the file must
 	 * be shared and the user must have direct access to that file; an error
@@ -101,6 +104,12 @@ public function getRoom(string $fileId): DataResponse {
 			$room = $this->manager->createPublicRoom($node->getName(), 'file', $fileId);
 		}
 
+		try {
+			$room->getParticipant($this->currentUser);
+		} catch (ParticipantNotFoundException $e) {
+			$room->addUsers(['userId' => $this->currentUser]);
+		}
+
 		return new DataResponse([
 			'token' => $room->getToken()
 		]);
diff --git a/lib/Controller/RoomController.php b/lib/Controller/RoomController.php
index 73750a49052..81c4c7f6ff2 100644
--- a/lib/Controller/RoomController.php
+++ b/lib/Controller/RoomController.php
@@ -31,6 +31,7 @@
 use OCA\Spreed\Exceptions\InvalidPasswordException;
 use OCA\Spreed\Exceptions\ParticipantNotFoundException;
 use OCA\Spreed\Exceptions\RoomNotFoundException;
+use OCA\Spreed\Exceptions\UnauthorizedException;
 use OCA\Spreed\GuestManager;
 use OCA\Spreed\Manager;
 use OCA\Spreed\Participant;
@@ -1084,14 +1085,17 @@ public function joinRoom(string $token, string $password = ''): DataResponse {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
+		$user = $this->userManager->get($this->userId);
 		try {
-			if ($this->userId !== null) {
-				$newSessionId = $room->joinRoom($this->userId, $password, $this->session->getPasswordForRoom($token) === $room->getToken());
+			if ($user instanceof IUser) {
+				$newSessionId = $room->joinRoom($user, $password, $this->session->getPasswordForRoom($token) === $room->getToken());
 			} else {
 				$newSessionId = $room->joinRoomGuest($password, $this->session->getPasswordForRoom($token) === $room->getToken());
 			}
 		} catch (InvalidPasswordException $e) {
 			return new DataResponse([], Http::STATUS_FORBIDDEN);
+		} catch (UnauthorizedException $e) {
+			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
 		$this->session->removePasswordForRoom($token);
diff --git a/lib/Exceptions/UnauthorizedException.php b/lib/Exceptions/UnauthorizedException.php
new file mode 100644
index 00000000000..fb297212bf2
--- /dev/null
+++ b/lib/Exceptions/UnauthorizedException.php
@@ -0,0 +1,27 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Joas Schilling <coding@schilljs.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+
+namespace OCA\Spreed\Exceptions;
+
+class UnauthorizedException extends \Exception {
+
+}
diff --git a/lib/Files/Listener.php b/lib/Files/Listener.php
index 965c662d152..5ee4016a843 100644
--- a/lib/Files/Listener.php
+++ b/lib/Files/Listener.php
@@ -24,6 +24,7 @@
 
 namespace OCA\Spreed\Files;
 
+use OCA\Spreed\Exceptions\UnauthorizedException;
 use OCA\Spreed\Room;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\EventDispatcher\GenericEvent;
@@ -35,8 +36,9 @@
  * specific shared file, for example, when collaboratively editing it. The room
  * is persistent and can be accessed simultaneously by any user with direct
  * access (user, group, circle and room share, but not link share, for example)
- * to that file. The room has no owner, and there are no persistent participants
- * (it is a public room that users join and leave on each session).
+ * to that file. The room has no owner, although self joined users become
+ * persistent participants automatically when they join until they explicitly
+ * leave or no longer have access to the file.
  *
  * These rooms are associated to a "file" object, and their custom behaviour is
  * provided by calling the methods of this class as a response to different room
@@ -58,14 +60,22 @@ public function register() {
 		$listener = function(GenericEvent $event) {
 			/** @var Room $room */
 			$room = $event->getSubject();
-			$this->preventUsersWithoutDirectAccessToTheFileFromJoining($room, $event->getArgument('userId'));
+			try {
+				$this->preventUsersWithoutDirectAccessToTheFileFromJoining($room, $event->getArgument('userId'));
+			} catch (UnauthorizedException $e) {
+				$event->setArgument('cancel', true);
+			}
 		};
 		$this->dispatcher->addListener(Room::class . '::preJoinRoom', $listener);
 
 		$listener = function(GenericEvent $event) {
 			/** @var Room $room */
 			$room = $event->getSubject();
-			$this->preventGuestsFromJoining($room);
+			try {
+				$this->preventGuestsFromJoining($room);
+			} catch (UnauthorizedException $e) {
+				$event->setArgument('cancel', true);
+			}
 		};
 		$this->dispatcher->addListener(Room::class . '::preJoinRoomGuest', $listener);
 	}
@@ -82,7 +92,7 @@ public function register() {
 	 *
 	 * @param Room $room
 	 * @param string $userId
-	 * @throws \Exception
+	 * @throws UnauthorizedException
 	 */
 	public function preventUsersWithoutDirectAccessToTheFileFromJoining(Room $room, string $userId) {
 		if ($room->getObjectType() !== 'file') {
@@ -91,7 +101,7 @@ public function preventUsersWithoutDirectAccessToTheFileFromJoining(Room $room,
 
 		$share = $this->util->getAnyDirectShareOfFileAccessibleByUser($room->getObjectId(), $userId);
 		if (!$share) {
-			throw new \Exception('User does not have direct access to the file');
+			throw new UnauthorizedException('User does not have direct access to the file');
 		}
 	}
 
@@ -101,14 +111,14 @@ public function preventUsersWithoutDirectAccessToTheFileFromJoining(Room $room,
 	 * This method should be called before a guest joins a room.
 	 *
 	 * @param Room $room
-	 * @throws \Exception
+	 * @throws UnauthorizedException
 	 */
 	public function preventGuestsFromJoining(Room $room) {
 		if ($room->getObjectType() !== 'file') {
 			return;
 		}
 
-		throw new \Exception('Guests are not allowed in rooms for files');
+		throw new UnauthorizedException('Guests are not allowed in rooms for files');
 	}
 
 }
diff --git a/lib/Room.php b/lib/Room.php
index 51e0c770c5a..bc1b4cb2275 100644
--- a/lib/Room.php
+++ b/lib/Room.php
@@ -27,6 +27,7 @@
 
 use OCA\Spreed\Exceptions\InvalidPasswordException;
 use OCA\Spreed\Exceptions\ParticipantNotFoundException;
+use OCA\Spreed\Exceptions\UnauthorizedException;
 use OCP\Comments\IComment;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\IDBConnection;
@@ -596,24 +597,31 @@ public function removeParticipantBySession(Participant $participant) {
 	}
 
 	/**
-	 * @param string $userId
+	 * @param IUser $user
 	 * @param string $password
 	 * @param bool $passedPasswordProtection
 	 * @return string
 	 * @throws InvalidPasswordException
+	 * @throws UnauthorizedException
 	 */
-	public function joinRoom($userId, $password, $passedPasswordProtection = false) {
-		$this->dispatcher->dispatch(self::class . '::preJoinRoom', new GenericEvent($this, [
-			'userId' => $userId,
+	public function joinRoom(IUser $user, $password, $passedPasswordProtection = false) {
+		$event = new GenericEvent($this, [
+			'userId' => $user->getUID(),
 			'password' => $password,
 			'passedPasswordProtection' => $passedPasswordProtection,
-		]));
+		]);
+		$this->dispatcher->dispatch(self::class . '::preJoinRoom', $event);
+
+		if ($event->hasArgument('cancel') && $event->getArgument('cancel') === true) {
+			$this->removeUser($user);
+			throw new UnauthorizedException('Participant is not allowed to join');
+		}
 
 		$query = $this->db->getQueryBuilder();
 		$query->update('talk_participants')
 			->set('session_id', $query->createParameter('session_id'))
 			->where($query->expr()->eq('room_id', $query->createNamedParameter($this->getId(), IQueryBuilder::PARAM_INT)))
-			->andWhere($query->expr()->eq('user_id', $query->createNamedParameter($userId)));
+			->andWhere($query->expr()->eq('user_id', $query->createNamedParameter($user->getUID())));
 
 		$sessionId = $this->secureRandom->generate(255);
 		$query->setParameter('session_id', $sessionId);
@@ -626,7 +634,7 @@ public function joinRoom($userId, $password, $passedPasswordProtection = false)
 
 			// User joining a public room, without being invited
 			$this->addUsers([
-				'userId' => $userId,
+				'userId' => $user->getUID(),
 				'participantType' => Participant::USER_SELF_JOINED,
 				'sessionId' => $sessionId,
 			]);
@@ -639,7 +647,7 @@ public function joinRoom($userId, $password, $passedPasswordProtection = false)
 		}
 
 		$this->dispatcher->dispatch(self::class . '::postJoinRoom', new GenericEvent($this, [
-			'userId' => $userId,
+			'userId' => $user->getUID(),
 			'password' => $password,
 			'passedPasswordProtection' => $passedPasswordProtection,
 		]));
@@ -692,9 +700,15 @@ public function leaveRoom($userId) {
 	 * @param bool $passedPasswordProtection
 	 * @return string
 	 * @throws InvalidPasswordException
+	 * @throws UnauthorizedException
 	 */
 	public function joinRoomGuest($password, $passedPasswordProtection = false) {
-		$this->dispatcher->dispatch(self::class . '::preJoinRoomGuest', new GenericEvent($this));
+		$event = new GenericEvent($this);
+		$this->dispatcher->dispatch(self::class . '::preJoinRoomGuest', $event);
+
+		if ($event->hasArgument('cancel') && $event->getArgument('cancel') === true) {
+			throw new UnauthorizedException('Participant is not allowed to join');
+		}
 
 		if (!$passedPasswordProtection && !$this->verifyPassword($password)['result']) {
 			throw new InvalidPasswordException();