Index: wp-includes/class-wp-editor.php
===================================================================
--- wp-includes/class-wp-editor.php	(revision 19802)
+++ wp-includes/class-wp-editor.php	(working copy)
@@ -303,7 +303,8 @@
 					'gecko_spellcheck' => true,
 					'fix_list_elements' => true,
 					'keep_styles' => false,
-					'entities' => '38,amp,60,lt,62,gt',
+					'entities' => '160,nbsp,38,amp,60,lt,62,gt',
+					'entity_encoding' => 'named',
 					'accessibility_focus' => true,
 					'tabfocus_elements' => 'title,publish',
 					'media_strict' => false,