diff --git a/wp-includes/taxonomy.php b/wp-includes/taxonomy.php
index 820d66c1f..f04892619 100644
--- a/wp-includes/taxonomy.php
+++ b/wp-includes/taxonomy.php
@@ -29,12 +29,12 @@ function create_initial_taxonomies() {
 			'category' => array(
 				'hierarchical' => true,
 				'slug' => get_option('category_base') ? get_option('category_base') : 'category',
-				'with_front' => get_option('category_base') || $wp_rewrite->using_index_permalinks(),
+				'with_front' => ! get_option('category_base') || $wp_rewrite->using_index_permalinks(),
 				'ep_mask' => EP_CATEGORIES,
 			),
 			'post_tag' => array(
 				'slug' => get_option('tag_base') ? get_option('tag_base') : 'tag',
-				'with_front' => get_option('tag_base') || $wp_rewrite->using_index_permalinks(),
+				'with_front' => ! get_option('tag_base') || $wp_rewrite->using_index_permalinks(),
 				'ep_mask' => EP_TAGS,
 			),
 			'post_format' => $post_format_base ? array( 'slug' => $post_format_base ) : false,