diff --git a/classes/helpers.php b/classes/helpers.php
index 5f7bcdf..89ac853 100644
--- a/classes/helpers.php
+++ b/classes/helpers.php
@@ -35,7 +35,7 @@ public static function original_option_id( $post_id ) {
 			$post_id = 'options';
 		}
 
-		return str_replace( sprintf( '_%s', pll_current_language( 'locale' ) ), '', $post_id );
+		return $post_id ? str_replace( sprintf( '_%s', pll_current_language( 'locale' ) ), '', $post_id ) : 0;
 	}
 
 
diff --git a/classes/main.php b/classes/main.php
index b2638fb..d3a9f14 100644
--- a/classes/main.php
+++ b/classes/main.php
@@ -47,7 +47,7 @@ public function set_current_site_lang() {
 	 *
 	 */
 	public function get_default_reference( $reference, $field_name, $post_id ) {
-		if ( ! empty( $reference ) ) {
+		if ( ! empty( $reference ) || !$post_id ) {
 			return $reference;
 		}