diff --git a/src/calibre/gui2/actions/delete.py b/src/calibre/gui2/actions/delete.py
index 718f0737b3..43465512e0 100644
--- a/src/calibre/gui2/actions/delete.py
+++ b/src/calibre/gui2/actions/delete.py
@@ -152,7 +152,8 @@ class DeleteAction(InterfaceAction):
         if not ids:
             return
         fmts = self._get_selected_formats(
-            '<p>'+_('Choose formats <b>not</b> to be deleted'), ids)
+            '<p>'+_('Choose formats <b>not</b> to be deleted.<p>Note that '
+                'this will never remove all formats from a book.'), ids)
         if fmts is None:
             return
         for id in ids:
@@ -161,9 +162,12 @@ class DeleteAction(InterfaceAction):
                 continue
             bfmts = set([x.lower() for x in bfmts.split(',')])
             rfmts = bfmts - set(fmts)
-            for fmt in rfmts:
-                self.gui.library_view.model().db.remove_format(id, fmt,
-                        index_is_id=True, notify=False)
+            if bfmts - rfmts:
+                # Do not delete if it will leave the book with no
+                # formats
+                for fmt in rfmts:
+                    self.gui.library_view.model().db.remove_format(id, fmt,
+                            index_is_id=True, notify=False)
         self.gui.library_view.model().refresh_ids(ids)
         self.gui.library_view.model().current_changed(self.gui.library_view.currentIndex(),
                 self.gui.library_view.currentIndex())
diff --git a/src/calibre/gui2/dialogs/select_formats.py b/src/calibre/gui2/dialogs/select_formats.py
index 5934c8c0f9..aea56ad196 100644
--- a/src/calibre/gui2/dialogs/select_formats.py
+++ b/src/calibre/gui2/dialogs/select_formats.py
@@ -44,7 +44,7 @@ class SelectFormats(QDialog):
         self.setLayout(self._l)
         self.setWindowTitle(_('Choose formats'))
         self._m = QLabel(msg)
-        self._m.setWordWrap = True
+        self._m.setWordWrap(True)
         self._l.addWidget(self._m)
         self.formats = Formats(fmt_list)
         self.fview = QListView(self)