diff --git a/wp-includes/class-wp-tax-query.php b/wp-includes/class-wp-tax-query.php
index 1432245cc0..795309b498 100644
--- a/wp-includes/class-wp-tax-query.php
+++ b/wp-includes/class-wp-tax-query.php
@@ -556,7 +556,11 @@ class WP_Tax_Query {
 			return;
 		}
 
-		$query['terms'] = array_unique( (array) $query['terms'] );
+		if ( 'slug' === $query['field'] || 'name' === $query['field'] ) {
+			$query['terms'] = array_unique( (array) $query['terms'] );
+		} else {
+			$query['terms'] = wp_parse_id_list( $query['terms'] );
+		}
 
 		if ( is_taxonomy_hierarchical( $query['taxonomy'] ) && $query['include_children'] ) {
 			$this->transform_query( $query, 'term_id' );