Index: src/wp-content/themes/twentyfifteen/single.php
===================================================================
--- src/wp-content/themes/twentyfifteen/single.php	(revision 30827)
+++ src/wp-content/themes/twentyfifteen/single.php	(working copy)
@@ -30,8 +30,12 @@
 
 			// Previous/next post navigation.
 			the_post_navigation( array(
-				'next_text' => _x( '<span class="meta-nav">Next <span class="screen-reader-text">post: </span></span><span class="post-title">%title</span>', 'Next post link', 'twentyfifteen' ),
-				'prev_text' => _x( '<span class="meta-nav">Previous <span class="screen-reader-text">post: </span></span><span class="post-title">%title</span>', 'Previous post link', 'twentyfifteen' )
+				'next_text' => '<span class="meta-nav" aria-hidden="true">' . __( 'Next', 'twentyfifteen' ) . '</span> ' .
+					'<span class="screen-reader-text">' . __( 'Next post:', 'twentyfifteen' ) . '</span> ' .
+					'<span class="post-title">%title</span>',
+				'prev_text' => '<span class="meta-nav" aria-hidden="true">' . __( 'Previous', 'twentyfifteen' ) . '</span> ' .
+					'<span class="screen-reader-text">' . __( 'Previous post:', 'twentyfifteen' ) . '</span> ' .
+					'<span class="post-title">%title</span>',
 			) );
 
 		// End the loop.