diff --git a/src/Content/Conversation.php b/src/Content/Conversation.php
index d9036c783..eb9af133c 100644
--- a/src/Content/Conversation.php
+++ b/src/Content/Conversation.php
@@ -970,7 +970,7 @@ class Conversation
 		}
 
 		$condition = DBA::mergeConditions($condition,
-			["`uid` IN (0, ?) AND (NOT `vid` IN (?, ?) OR `vid` IS NULL)", $uid, Verb::getID(Activity::FOLLOW), Verb::getID(Activity::VIEW)]);
+			["`uid` IN (0, ?) AND (NOT `vid` IN (?, ?, ?) OR `vid` IS NULL)", $uid, Verb::getID(Activity::FOLLOW), Verb::getID(Activity::VIEW), Verb::getID(Activity::READ)]);
 
 		$thread_parents = Post::select(['uri-id', 'causer-id'], $condition, ['order' => ['uri-id' => false, 'uid']]);
 
diff --git a/src/Protocol/Activity.php b/src/Protocol/Activity.php
index ea1feeefe..7212e9194 100644
--- a/src/Protocol/Activity.php
+++ b/src/Protocol/Activity.php
@@ -163,6 +163,13 @@ final class Activity
 	 * @var string
 	 */
 	const ANNOUNCE   = ActivityNamespace::ACTIVITY2 . 'Announce';
+	/**
+	 * Indicates that the actor has read the object.
+	 *
+	 * @see https://www.w3.org/TR/activitystreams-vocabulary/#dfn-read
+	 * @var string
+	 */
+	const READ       = ActivityNamespace::ACTIVITY2 . 'read';
 
 	const O_UNFOLLOW    = ActivityNamespace::OSTATUS . '/unfollow';
 	const O_UNFAVOURITE = ActivityNamespace::OSTATUS . '/unfavorite';
@@ -194,6 +201,7 @@ final class Activity
 		self::ANNOUNCE,
 		self::EMOJIREACT,
 		self::VIEW,
+		self::READ,
 	];
 
 	/**
diff --git a/src/Protocol/ActivityPub/Receiver.php b/src/Protocol/ActivityPub/Receiver.php
index 85965d712..41a3ca0ad 100644
--- a/src/Protocol/ActivityPub/Receiver.php
+++ b/src/Protocol/ActivityPub/Receiver.php
@@ -63,7 +63,7 @@ class Receiver
 	const PUBLIC_COLLECTION = 'as:Public';
 	const ACCOUNT_TYPES = ['as:Person', 'as:Organization', 'as:Service', 'as:Group', 'as:Application'];
 	const CONTENT_TYPES = ['as:Note', 'as:Article', 'as:Video', 'as:Image', 'as:Event', 'as:Audio', 'as:Page', 'as:Question'];
-	const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept'];
+	const ACTIVITY_TYPES = ['as:Like', 'as:Dislike', 'as:Accept', 'as:Reject', 'as:TentativeAccept', 'as:Read'];
 
 	const TARGET_UNKNOWN = 0;
 	const TARGET_TO = 1;
@@ -934,6 +934,9 @@ class Receiver
 				} elseif (in_array($object_data['object_type'], ['as:Delete'])) {
 					// We cannot undo deletions, so we just ignore this
 					Queue::remove($object_data);
+				} elseif (in_array($object_data['object_object_type'], ['as:Tombstone'])) {
+					// The object is a tombstone, we ignore any actions on it.
+					Queue::remove($object_data);
 				} else {
 					return false;
 				}
@@ -949,6 +952,16 @@ class Receiver
 					return false;
 				}
 				break;
+			case 'as:Read':
+				if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
+					ActivityPub\Processor::createActivity($object_data, Activity::READ);
+				} elseif ($object_data['object_type'] == '') {
+					// The object type couldn't be determined. Most likely we don't have it here. We ignore this activity.
+					Queue::remove($object_data);
+				} else {
+					return false;
+				}
+				break;
 
 			case 'litepub:EmojiReact':
 				if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {