diff --git a/composer.json b/composer.json
index 44b5406..1b3bb36 100644
--- a/composer.json
+++ b/composer.json
@@ -50,15 +50,17 @@
             "@test-vs-event-list",
             "@test-the-events-calendar",
             "@test-gatherpress",
-            "@test-events-manager"
+            "@test-events-manager",
+            "@test-wp-event-manager"
         ],
         "test-debug": [
             "@prepare-test",
-            "@test-gatherpress"
+            "@test-wp-event-manager"
         ],
         "test-vs-event-list": "phpunit --filter=vs_event_list",
         "test-the-events-calendar": "phpunit --filter=the_events_calendar",
         "test-gatherpress": "phpunit --filter=gatherpress",
-        "test-events-manager": "phpunit --filter=events_manager"
+        "test-events-manager": "phpunit --filter=events_manager",
+        "test-wp-event-manager": "phpunit --filter=wp_event_manager"
     }
 }
diff --git a/includes/activitypub/transformer/class-wp-event-manager.php b/includes/activitypub/transformer/class-wp-event-manager.php
index f66d061..1e6c3bd 100644
--- a/includes/activitypub/transformer/class-wp-event-manager.php
+++ b/includes/activitypub/transformer/class-wp-event-manager.php
@@ -63,20 +63,31 @@ final class WP_Event_Manager extends Event_Transformer {
 
 	/**
 	 * Get the end time from the events metadata.
+	 *
+	 * @return ?string The events end-datetime if is set, null otherwise.
 	 */
 	public function get_end_time(): ?string {
-		$end_date     = get_post_meta( $this->wp_object->ID, '_event_end_date', true );
-		$end_datetime = new DateTime( $end_date );
-		return \gmdate( 'Y-m-d\TH:i:s\Z', $end_datetime->getTimestamp() );
+		$end_date = get_post_meta( $this->wp_object->ID, '_event_end_date', true );
+		if ( $end_date ) {
+			$end_datetime = new DateTime( $end_date );
+			return \gmdate( 'Y-m-d\TH:i:s\Z', $end_datetime->getTimestamp() );
+		}
+		return null;
 	}
 
 	/**
 	 * Get the end time from the events metadata.
 	 */
 	public function get_start_time(): string {
-		$start_date     = get_post_meta( $this->wp_object->ID, '_event_start_date', true );
-		$start_datetime = new DateTime( $start_date );
-		return \gmdate( 'Y-m-d\TH:i:s\Z', $start_datetime->getTimestamp() );
+		$start_date = get_post_meta( $this->wp_object->ID, '_event_start_date', true );
+		if ( ! is_numeric( $start_date ) ) {
+			$start_datetime  = new DateTime( $start_date );
+			$start_timestamp = $start_datetime->getTimestamp();
+		} else {
+			$start_timestamp = (int) $start_date;
+		}
+
+		return \gmdate( 'Y-m-d\TH:i:s\Z', $start_timestamp );
 	}
 
 	/**
diff --git a/tests/test-class-plugin-vs-event-list.php b/tests/test-class-plugin-vs-event-list.php
index 48e513d..d15e7ef 100644
--- a/tests/test-class-plugin-vs-event-list.php
+++ b/tests/test-class-plugin-vs-event-list.php
@@ -44,7 +44,7 @@ class Test_VS_Event_List extends WP_UnitTestCase {
 		$wp_post_id = wp_insert_post(
 			array(
 				'post_title'  => 'VSEL Test Event',
-				'post_status' => 'published',
+				'post_status' => 'publish',
 				'post_type'   => 'event',
 				'meta_input'  => array(
 					'event-start-date' => strtotime( '+10 days 15:00:00' ),
@@ -69,7 +69,7 @@ class Test_VS_Event_List extends WP_UnitTestCase {
 		$wp_post_id = wp_insert_post(
 			array(
 				'post_title'  => 'VSEL Test Event',
-				'post_status' => 'published',
+				'post_status' => 'publish',
 				'post_type'   => 'event',
 				'meta_input'  => array(
 					'event-start-date' => strtotime( '+10 days 15:00:00' ),
@@ -102,7 +102,7 @@ class Test_VS_Event_List extends WP_UnitTestCase {
 		$wp_post_id = wp_insert_post(
 			array(
 				'post_title'  => 'VSEL Test Event',
-				'post_status' => 'published',
+				'post_status' => 'publish',
 				'post_type'   => 'event',
 				'meta_input'  => array(
 					'event-start-date' => strtotime( '+10 days 15:00:00' ),
@@ -147,7 +147,7 @@ class Test_VS_Event_List extends WP_UnitTestCase {
 		$wp_post_id = wp_insert_post(
 			array(
 				'post_title'  => 'VSEL Test Event',
-				'post_status' => 'published',
+				'post_status' => 'publish',
 				'post_type'   => 'event',
 				'meta_input'  => array(
 					'event-start-date'    => strtotime( '+10 days 15:00:00' ),
@@ -182,7 +182,7 @@ class Test_VS_Event_List extends WP_UnitTestCase {
 		$wp_post_id = wp_insert_post(
 			array(
 				'post_title'  => 'VSEL Test Event',
-				'post_status' => 'published',
+				'post_status' => 'publish',
 				'post_type'   => 'event',
 				'meta_input'  => array(
 					'event-start-date'    => strtotime( '+10 days 15:00:00' ),
diff --git a/tests/test-class-plugin-wp-event-manager.php b/tests/test-class-plugin-wp-event-manager.php
index bee4a4c..3cfd488 100644
--- a/tests/test-class-plugin-wp-event-manager.php
+++ b/tests/test-class-plugin-wp-event-manager.php
@@ -44,7 +44,7 @@ class Test_WP_Event_Manager extends WP_UnitTestCase {
 		$wp_post_id = wp_insert_post(
 			array(
 				'post_title'  => 'WP Event Manager TestEvent',
-				'post_status' => 'published',
+				'post_status' => 'publish',
 				'post_type'   => 'event_listing',
 				'meta_input'  => array(
 					'event-start-date' => strtotime( '+10 days 15:00:00' ),
@@ -69,7 +69,7 @@ class Test_WP_Event_Manager extends WP_UnitTestCase {
 		$wp_post_id = wp_insert_post(
 			array(
 				'post_title'   => 'WP Event Manager TestEvent',
-				'post_status'  => 'published',
+				'post_status'  => 'publish',
 				'post_type'    => 'event_listing',
 				'post_content' => 'Come to my WP Event Manager event!',
 				'meta_input'   => array(
@@ -104,7 +104,7 @@ class Test_WP_Event_Manager extends WP_UnitTestCase {
 		$wp_post_id = wp_insert_post(
 			array(
 				'post_title'   => 'WP Event Manager TestEvent',
-				'post_status'  => 'published',
+				'post_status'  => 'publish',
 				'post_type'    => 'event_listing',
 				'post_content' => 'Come to my WP Event Manager event!',
 				'meta_input'   => array(