diff --git a/src/calibre/ebooks/mobi/writer2/main.py b/src/calibre/ebooks/mobi/writer2/main.py
index 0336fcdff0..93b3987971 100644
--- a/src/calibre/ebooks/mobi/writer2/main.py
+++ b/src/calibre/ebooks/mobi/writer2/main.py
@@ -161,7 +161,7 @@ class MobiWriter(object):
         index = 1
 
         mh_href = None
-        if 'masthead' in oeb.guide:
+        if 'masthead' in oeb.guide and oeb.guide['masthead'].href:
             mh_href = oeb.guide['masthead'].href
             self.image_records.append(None)
             index += 1
diff --git a/src/calibre/gui2/dialogs/scheduler.py b/src/calibre/gui2/dialogs/scheduler.py
index 9d103d5ca5..23d6bbcef4 100644
--- a/src/calibre/gui2/dialogs/scheduler.py
+++ b/src/calibre/gui2/dialogs/scheduler.py
@@ -441,7 +441,7 @@ class Scheduler(QObject):
         self.news_menu.addAction(self.cac)
         self.news_menu.addSeparator()
         self.all_action = self.news_menu.addAction(
-                _('Download all scheduled new sources'),
+                _('Download all scheduled news sources'),
                 self.download_all_scheduled)
 
         self.timer = QTimer(self)