Index: src/wp-admin/includes/theme.php
===================================================================
--- src/wp-admin/includes/theme.php	(revision 42710)
+++ src/wp-admin/includes/theme.php	(working copy)
@@ -744,7 +744,7 @@
 
 			<div class="theme-actions">
 				<# if ( data.active ) { #>
-					<button type="button" class="button button-primary customize-theme"><?php _e( 'Customize' ); ?></a>
+					<button type="button" class="button button-primary customize-theme"><?php _e( 'Customize' ); ?></button>
 				<# } else if ( 'installed' === data.type ) { #>
 					<?php if ( current_user_can( 'delete_themes' ) ) { ?>
 						<# if ( data.actions && data.actions['delete'] ) { #>
@@ -751,7 +751,7 @@
 							<a href="{{{ data.actions['delete'] }}}" data-slug="{{ data.id }}" class="button button-secondary delete-theme"><?php _e( 'Delete' ); ?></a>
 						<# } #>
 					<?php } ?>
-					<button type="button" class="button button-primary preview-theme" data-slug="{{ data.id }}"><?php _e( 'Live Preview' ); ?></span>
+					<button type="button" class="button button-primary preview-theme" data-slug="{{ data.id }}"><?php _e( 'Live Preview' ); ?></button>
 				<# } else { #>
 					<button type="button" class="button theme-install" data-slug="{{ data.id }}"><?php _e( 'Install' ); ?></button>
 					<button type="button" class="button button-primary theme-install preview" data-slug="{{ data.id }}"><?php _e( 'Install &amp; Preview' ); ?></button>