diff --git a/src/wp-includes/taxonomy.php b/src/wp-includes/taxonomy.php
index fe2bee4430..44d9dfb476 100644
--- a/src/wp-includes/taxonomy.php
+++ b/src/wp-includes/taxonomy.php
@@ -1238,7 +1238,7 @@ function get_terms($taxonomies, $args = '') {
 	$args = wp_parse_args( $args, $defaults );
 	$args['number'] = absint( $args['number'] );
 	$args['offset'] = absint( $args['offset'] );
-	if ( !$single_taxonomy || !is_taxonomy_hierarchical($taxonomies[0]) ||
+	if ( !$single_taxonomy || ! is_taxonomy_hierarchical( reset( $taxonomies ) ) ||
 		'' !== $args['parent'] ) {
 		$args['child_of'] = 0;
 		$args['hierarchical'] = false;
diff --git a/tests/phpunit/tests/term/getTerms.php b/tests/phpunit/tests/term/getTerms.php
index 05f771f70c..eb576e659a 100644
--- a/tests/phpunit/tests/term/getTerms.php
+++ b/tests/phpunit/tests/term/getTerms.php
@@ -85,7 +85,7 @@ class Tests_Term_getTerms extends WP_UnitTestCase {
 	function test_get_terms_should_allow_arbitrary_indexed_taxonomies_array() {
 		$term_id = $this->factory->tag->create();
 		$terms = get_terms( array( '111' => 'post_tag' ), array( 'hide_empty' => false ) );
-		$this->assertEquals( $term_id, $terms[0]->term_id );
+		$this->assertEquals( $term_id, reset( $terms )->term_id );
 	}
 
 	/**