diff --git a/wp-includes/meta.php b/wp-includes/meta.php
index ff32086..f9cf57b 100644
--- a/wp-includes/meta.php
+++ b/wp-includes/meta.php
@@ -1131,9 +1131,8 @@ function registered_meta_key_exists( $object_type, $object_subtype, $meta_key )
 		return false;
 	}
 
-	// Only specific core object types are supported.
 	if ( ! wp_object_type_exists( $object_type ) ) {
-		return new WP_Error( 'invalid_meta_key', __( 'Invalid meta key. Not a core object type.' ) );
+		return false;
 	}
 
 	if ( ! isset( $wp_meta_keys[ $object_type ] ) ) {
@@ -1165,6 +1164,11 @@ function registered_meta_key_exists( $object_type, $object_subtype, $meta_key )
 function unregister_meta_key( $object_type, $object_subtype, $meta_key ) {
 	global $wp_meta_keys;
 
+	// Only specific core object types are supported.
+	if ( ! wp_object_type_exists( $object_type ) ) {
+		return new WP_Error( 'invalid_meta_key', __( 'Invalid meta key. Not a core object type.' ) );
+	}
+
 	if ( ! registered_meta_key_exists( $object_type, $object_subtype, $meta_key ) ) {
 		return new WP_Error( 'invalid_meta_key', __( 'Invalid meta key' ) );
 	}