diff --git a/wp-includes/category-template.php b/wp-includes/category-template.php
index f42b039490..a5257dbe7c 100644
--- a/wp-includes/category-template.php
+++ b/wp-includes/category-template.php
@@ -127,7 +127,7 @@ function get_the_category( $id = false ) {
 	$categories = get_object_term_cache( $id, 'category' );
 	if ( false === $categories ) {
 		$categories = wp_get_object_terms( $id, 'category' );
-		wp_cache_add($post->ID, $categories, 'category_relationships');
+		wp_cache_add($id, $categories, 'category_relationships');
 	}
 
 	if ( !empty( $categories ) )