--- /wp-includes/category-template.php
+++ /wp-includes/category-template.php
@@ -618,7 +618,7 @@
 	$defaults = array(
 		'smallest' => 8, 'largest' => 22, 'unit' => 'pt', 'number' => 0,
 		'format' => 'flat', 'orderby' => 'name', 'order' => 'ASC',
-		'single_text' => '%d topic', 'multiple_text' => '%d topics'
+		'single_text' => __('%d topic'), 'multiple_text' => __('%d topics')
 	);
 	$args = wp_parse_args( $args, $defaults );
 	extract( $args );