diff --git a/src/Protocol/ActivityPub/Processor.php b/src/Protocol/ActivityPub/Processor.php
index 045c48a4c1..a5f6607edc 100644
--- a/src/Protocol/ActivityPub/Processor.php
+++ b/src/Protocol/ActivityPub/Processor.php
@@ -198,6 +198,43 @@ class Processor
 		Item::delete(['uri' => $activity['object_id'], 'owner-id' => $owner]);
 	}
 
+	/**
+	 * Prepare the item array for an activity
+	 *
+	 * @param array $activity Activity array
+	 * @throws \Friendica\Network\HTTPException\InternalServerErrorException
+	 * @throws \ImagickException
+	 */
+	public static function addTag($activity)
+	{
+		if (empty($activity['object_content']) || empty($activity['object_id'])) {
+			return;
+		}
+
+		foreach ($activity['receiver'] as $receiver) {
+			$item = Item::selectFirst(['id', 'tag', 'origin', 'author-link'], ['uri' => $activity['target_id'], 'uid' => $receiver]);
+			if (!DBA::isResult($item)) {
+				// We don't fetch missing content for this purpose
+				continue;
+			}
+
+			if (($item['author-link'] != $activity['actor']) && !$item['origin']) {
+				Logger::info('Not origin, not from the author, skipping update', ['id' => $item['id'], 'author' => $item['author-link'], 'actor' => $activity['actor']]);
+				continue;
+			}
+
+			// To-Do:
+			// - Check if "blocktag" is set
+			// - Check if actor is a contact
+
+			if (!stristr($item['tag'], trim($activity['object_content']))) {
+				$tag = $item['tag'] . (strlen($item['tag']) ? ',' : '') . '#[url=' . $activity['object_id'] . ']'. $activity['object_content'] . '[/url]';
+				Item::update(['tag' => $tag], ['id' => $item['id']]);
+				Logger::info('Tagged item', ['id' => $item['id'], 'tag' => $activity['object_content'], 'uri' => $activity['target_id'], 'actor' => $activity['actor']]);
+			}
+		}
+	}
+
 	/**
 	 * Prepare the item array for an activity
 	 *
diff --git a/src/Protocol/ActivityPub/Receiver.php b/src/Protocol/ActivityPub/Receiver.php
index 74d9392752..97bd7dc7e7 100644
--- a/src/Protocol/ActivityPub/Receiver.php
+++ b/src/Protocol/ActivityPub/Receiver.php
@@ -226,6 +226,13 @@ class Receiver
 			$object_data['author'] = JsonLD::fetchElement($activity, 'as:actor', '@id');
 			$object_data['object_id'] = $object_id;
 			$object_data['object_type'] = ''; // Since we don't fetch the object, we don't know the type
+		} elseif (in_array($type, ['as:Add'])) {
+			$object_data = [];
+			$object_data['id'] = JsonLD::fetchElement($activity, '@id');
+			$object_data['target_id'] = JsonLD::fetchElement($activity, 'as:target', '@id');
+			$object_data['object_id'] = JsonLD::fetchElement($activity, 'as:object', '@id');
+			$object_data['object_type'] = JsonLD::fetchElement($activity['as:object'], '@type');
+			$object_data['object_content'] = JsonLD::fetchElement($activity['as:object'], 'as:content', '@type');
 		} else {
 			$object_data = [];
 			$object_data['id'] = JsonLD::fetchElement($activity, '@id');
@@ -366,6 +373,12 @@ class Receiver
 				}
 				break;
 
+			case 'as:Add':
+				if ($object_data['object_type'] == 'as:tag') {
+					ActivityPub\Processor::addTag($object_data);
+				}
+				break;
+
 			case 'as:Announce':
 				if (in_array($object_data['object_type'], self::CONTENT_TYPES)) {
 					$profile = APContact::getByURL($object_data['actor']);