diff --git a/includes/classes/NS_Post_Finder.php b/includes/classes/NS_Post_Finder.php
index 514b2e1..e4d8537 100644
--- a/includes/classes/NS_Post_Finder.php
+++ b/includes/classes/NS_Post_Finder.php
@@ -505,7 +505,11 @@ public function search_posts() {
 		// Sanitize tax_queries
 		if ( isset( $_POST['tax_query'] ) ) {
 			foreach ( $_POST['tax_query'] as $current_tax_query ) {
-				$args['tax_query'][] = array_map( 'sanitize_text_field', $current_tax_query );
+				if ( is_array( $current_tax_query ) ) {
+					$args['tax_query'][] = array_map( 'sanitize_text_field', $current_tax_query );
+				} else {
+					$args['tax_query'][] = sanitize_text_field( $current_tax_query );
+				}
 			}
 		}