diff --git a/wp-includes/locale.php b/wp-includes/locale.php
index 227e52c58..bc5037c72 100644
--- a/wp-includes/locale.php
+++ b/wp-includes/locale.php
@@ -180,6 +180,7 @@ class WP_Locale {
 		// Set text direction.
 		if ( isset( $GLOBALS['text_direction'] ) )
 			$this->text_direction = $GLOBALS['text_direction'];
+		/* translators: 'rtl' or 'ltr'. This sets the text direction for WordPress. */
 		elseif ( 'rtl' == _x( 'ltr', 'text direction' ) )
 			$this->text_direction = 'rtl';
 	}