diff --git a/src/calibre/gui2/dialogs/comments_dialog.py b/src/calibre/gui2/dialogs/comments_dialog.py
index 2734a1bd21..eee23f4b3e 100644
--- a/src/calibre/gui2/dialogs/comments_dialog.py
+++ b/src/calibre/gui2/dialogs/comments_dialog.py
@@ -18,8 +18,8 @@ class CommentsDialog(QDialog, Ui_CommentsDialog):
         self.setWindowFlags(self.windowFlags()&(~Qt.WindowContextHelpButtonHint))
         self.setWindowIcon(icon)
 
-        if text is not None:
-            self.textbox.html = comments_to_html(text)
+        self.textbox.html = comments_to_html(text) if text else ''
+        self.textbox.wyswyg_dirtied()
         # self.textbox.setTabChangesFocus(True)
         self.buttonBox.button(QDialogButtonBox.Ok).setText(_('&OK'))
         self.buttonBox.button(QDialogButtonBox.Cancel).setText(_('&Cancel'))