diff --git a/includes/activitypub/handler/class-create.php b/includes/activitypub/handler/class-create.php
index 411bbb3..d980551 100644
--- a/includes/activitypub/handler/class-create.php
+++ b/includes/activitypub/handler/class-create.php
@@ -22,7 +22,15 @@ class Create {
 	public static function init() {
 		\add_action(
 			'activitypub_inbox_create',
-			array( self::class, 'handle_create' )
+			array( self::class, 'handle_create' ),
+			15,
+			2
+		);
+		\add_filter(
+			'activitypub_validate_object',
+			array( self::class, 'validate_object' ),
+			12,
+			3
 		);
 	}
 
@@ -44,7 +52,7 @@ class Create {
 		}
 
 		// Check if an object is set.
-		if ( ! isset( $activity['object']['type'] ) || 'Event' !== isset( $activity['object']['type'] ) ) {
+		if ( ! isset( $activity['object']['type'] ) || 'Event' !== $activity['object']['type'] ) {
 			return;
 		}
 
@@ -57,4 +65,48 @@ class Create {
 		$transmogrifier = new $transmogrifier_class( $activity['object'] );
 		$transmogrifier->create();
 	}
+
+	/**
+	 * Validate the object.
+	 *
+	 * @param bool             $valid   The validation state.
+	 * @param string           $param   The object parameter.
+	 * @param \WP_REST_Request $request The request object.
+	 *
+	 * @return bool The validation state: true if valid, false if not.
+	 */
+	public static function validate_object( $valid, $param, $request ) {
+		$json_params = $request->get_json_params();
+
+		if ( isset( $json_params['object']['type'] ) && 'Event' === $json_params['object']['type'] ) {
+			$valid = true;
+		}
+
+		if ( empty( $json_params['type'] ) ) {
+			return false;
+		}
+
+		if (
+			'Create' !== $json_params['type'] ||
+			is_wp_error( $request )
+		) {
+			return $valid;
+		}
+
+		$object = $json_params['object'];
+
+		if ( ! is_array( $object ) ) {
+			return false;
+		}
+
+		$required = array(
+			'id',
+		);
+
+		if ( array_intersect( $required, array_keys( $object ) ) !== $required ) {
+			return false;
+		}
+
+		return $valid;
+	}
 }
diff --git a/includes/activitypub/transmogrifier/class-gatherpress.php b/includes/activitypub/transmogrifier/class-gatherpress.php
index 7db80d8..06c196d 100644
--- a/includes/activitypub/transmogrifier/class-gatherpress.php
+++ b/includes/activitypub/transmogrifier/class-gatherpress.php
@@ -55,7 +55,7 @@ class GatherPress {
 	/**
 	 * Save the ActivityPub event object as GatherPress Event.
 	 */
-	public function save() {
+	public function create() {
 		// Insert new GatherPress Event post.
 		$post_id = wp_insert_post(
 			array(
diff --git a/includes/class-settings.php b/includes/class-settings.php
index 02769ae..ab88721 100644
--- a/includes/class-settings.php
+++ b/includes/class-settings.php
@@ -144,7 +144,8 @@ class Settings {
 		$valid_options = array();
 		foreach ( $active_event_plugins as $active_event_plugin ) {
 			if ( $active_event_plugin->supports_event_sources() ) {
-				$valid_options[] = $active_event_plugin::class;
+				$full_class      = $active_event_plugin::class;
+				$valid_options[] = substr( $full_class, strrpos( $full_class, '\\' ) + 1 );
 			}
 		}
 		if ( in_array( $plugin, $valid_options, true ) ) {
diff --git a/includes/class-setup.php b/includes/class-setup.php
index 87bdb59..b0fd90c 100644
--- a/includes/class-setup.php
+++ b/includes/class-setup.php
@@ -366,8 +366,10 @@ class Setup {
 			return;
 		}
 		$active_event_plugins = $setup->get_active_event_plugins();
-		if ( array_key_exists( $event_plugin, $active_event_plugins ) ) {
-			return $active_event_plugins[ $event_plugin ]->get_transmogrifier_class();
+		foreach ( $active_event_plugins as $active_event_plugin ) {
+			if ( strrpos( $active_event_plugin::class, $event_plugin ) ) {
+				return $active_event_plugin::get_transmogrifier_class();
+			}
 		}
 	}
 }
diff --git a/includes/integrations/class-event-plugin.php b/includes/integrations/class-event-plugin.php
index 6c25b1a..a76e485 100644
--- a/includes/integrations/class-event-plugin.php
+++ b/includes/integrations/class-event-plugin.php
@@ -100,7 +100,7 @@ abstract class Event_Plugin {
 	 * Returns the class used for transmogrifying an Event (ActivityStreams to Event plugin transformation).
 	 */
 	public static function get_transmogrifier_class(): ?string {
-		if ( ! self::supports_event_sources() ) {
+		if ( ! static::supports_event_sources() ) {
 			return null;
 		}
 		return str_replace( 'Integrations', 'Activitypub\Transmogrifier', static::class );