Index: inc/template-tags.php
===================================================================
--- inc/template-tags.php	(revision 30761)
+++ inc/template-tags.php	(working copy)
@@ -52,7 +52,7 @@
 	$format = get_post_format();
 	if ( current_theme_supports( 'post-formats', $format ) ) {
 		printf( '<span class="entry-format">%1$s<a href="%2$s">%3$s</a></span>',
-			sprintf( '<span class="screen-reader-text">%s</span>', esc_html_x( 'Format', 'Used before post format.', 'twentyfifteen' ) ),
+			sprintf( '<span class="screen-reader-text">%s </span>', esc_html_x( 'Format', 'Used before post format.', 'twentyfifteen' ) ),
 			esc_url( get_post_format_link( $format ) ),
 			get_post_format_string( $format )
 		);
@@ -72,7 +72,7 @@
 			esc_html( get_the_modified_date() )
 		);
 
-		printf( '<span class="posted-on"><span class="screen-reader-text">%1$s</span><a href="%2$s" rel="bookmark">%3$s</a></span>',
+		printf( '<span class="posted-on"><span class="screen-reader-text">%1$s </span><a href="%2$s" rel="bookmark">%3$s</a></span>',
 			esc_html_x( 'Posted on', 'Used before publish date.', 'twentyfifteen' ),
 			esc_url( get_permalink() ),
 			$time_string
@@ -81,7 +81,7 @@
 
 	if ( 'post' == get_post_type() ) {
 		if ( is_singular() || is_multi_author() ) {
-			printf( '<span class="byline"><span class="author vcard"><span class="screen-reader-text">%1$s</span><a class="url fn n" href="%2$s">%3$s</a></span></span>',
+			printf( '<span class="byline"><span class="author vcard"><span class="screen-reader-text">%1$s </span><a class="url fn n" href="%2$s">%3$s</a></span></span>',
 				esc_html_x( 'Author', 'Used before post author name.', 'twentyfifteen' ),
 				esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ),
 				esc_html( get_the_author() )
@@ -90,7 +90,7 @@
 
 		$categories_list = get_the_category_list( _x( ', ', 'Used between list items, there is a space after the comma.', 'twentyfifteen' ) );
 		if ( $categories_list && twentyfifteen_categorized_blog() ) {
-			printf( '<span class="cat-links"><span class="screen-reader-text">%1$s</span>%2$s</span>',
+			printf( '<span class="cat-links"><span class="screen-reader-text">%1$s </span>%2$s</span>',
 				esc_html_x( 'Categories', 'Used before category names.', 'twentyfifteen' ),
 				$categories_list
 			);
@@ -98,7 +98,7 @@
 
 		$tags_list = get_the_tag_list( '', _x( ', ', 'Used between list items, there is a space after the comma.', 'twentyfifteen' ) );
 		if ( $tags_list ) {
-			printf( '<span class="tags-links"><span class="screen-reader-text">%1$s</span>%2$s</span>',
+			printf( '<span class="tags-links"><span class="screen-reader-text">%1$s </span>%2$s</span>',
 				esc_html_x( 'Tags', 'Used before tag names.', 'twentyfifteen' ),
 				$tags_list
 			);
@@ -109,7 +109,7 @@
 		// Retrieve attachment metadata.
 		$metadata = wp_get_attachment_metadata();
 
-		printf( '<span class="full-size-link"><span class="screen-reader-text">%1$s</span><a href="%2$s">%3$s &times; %4$s</a></span>',
+		printf( '<span class="full-size-link"><span class="screen-reader-text">%1$s </span><a href="%2$s">%3$s &times; %4$s</a></span>',
 			esc_html_x( 'Full size', 'Used before full size attachment link.', 'twentyfifteen' ),
 			esc_url( wp_get_attachment_url() ),
 			$metadata['width'],
Index: single.php
===================================================================
--- single.php	(revision 30761)
+++ single.php	(working copy)
@@ -30,8 +30,8 @@
 
 			// 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' => _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' )
 			) );
 
 		// End the loop.