diff --git a/src/calibre/gui2/library/models.py b/src/calibre/gui2/library/models.py
index 6725989ee5..b2a7f08055 100644
--- a/src/calibre/gui2/library/models.py
+++ b/src/calibre/gui2/library/models.py
@@ -72,7 +72,7 @@ class BooksModel(QAbstractTableModel): # {{{
                         'publisher' : _("Publisher"),
                         'tags'      : _("Tags"),
                         'series'    : _("Series"),
-                        }
+    }
 
     def __init__(self, parent=None, buffer=40):
         QAbstractTableModel.__init__(self, parent)
diff --git a/src/calibre/gui2/preferences/misc.py b/src/calibre/gui2/preferences/misc.py
index 99080c63bc..865115c2ed 100644
--- a/src/calibre/gui2/preferences/misc.py
+++ b/src/calibre/gui2/preferences/misc.py
@@ -106,8 +106,14 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         d.exec_()
 
     def compact(self, *args):
-        d = CheckIntegrity(self.gui.library_view.model().db, self)
+        from calibre.library.caches import MetadataBackup
+        m = self.gui.library_view.model()
+        if m.metadata_backup is not None:
+            m.metadata_backup.stop()
+        d = CheckIntegrity(m.db, self)
         d.exec_()
+        m.metadata_backup = MetadataBackup(m.db)
+        m.metadata_backup.start()
 
     def open_config_dir(self, *args):
         from calibre.utils.config import config_dir