diff --git a/lector/definitionsdialog.py b/lector/definitionsdialog.py
index d16fec1..aa8bbdf 100644
--- a/lector/definitionsdialog.py
+++ b/lector/definitionsdialog.py
@@ -38,8 +38,12 @@ class DefinitionsUI(QtWidgets.QDialog, definitions.Ui_Dialog):
         radius = 15
         path = QtGui.QPainterPath()
         path.addRoundedRect(QtCore.QRectF(self.rect()), radius, radius)
-        mask = QtGui.QRegion(path.toFillPolygon().toPolygon())
-        self.setMask(mask)
+
+        try:
+            mask = QtGui.QRegion(path.toFillPolygon().toPolygon())
+            self.setMask(mask)
+        except TypeError:  # Required for older versions of Qt
+            pass
 
         self.definitionView.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
 
diff --git a/lector/metadatadialog.py b/lector/metadatadialog.py
index c1e3c63..efa1781 100644
--- a/lector/metadatadialog.py
+++ b/lector/metadatadialog.py
@@ -36,8 +36,12 @@ class MetadataUI(QtWidgets.QDialog, metadata.Ui_Dialog):
         radius = 15
         path = QtGui.QPainterPath()
         path.addRoundedRect(QtCore.QRectF(self.rect()), radius, radius)
-        mask = QtGui.QRegion(path.toFillPolygon().toPolygon())
-        self.setMask(mask)
+
+        try:
+            mask = QtGui.QRegion(path.toFillPolygon().toPolygon())
+            self.setMask(mask)
+        except TypeError:  # Required for older versions of Qt
+            pass
 
         self.parent = parent
         self.database_path = self.parent.database_path
diff --git a/lector/settingsdialog.py b/lector/settingsdialog.py
index e474fc7..0c36b97 100644
--- a/lector/settingsdialog.py
+++ b/lector/settingsdialog.py
@@ -324,6 +324,8 @@ class SettingsUI(QtWidgets.QDialog, settingswindow.Ui_Dialog):
         self.gather_annotations()
         Settings(self.main_window).save_settings()
         Settings(self.main_window).read_settings()
+        self.main_window.settings['last_open_tab'] = None  # Needed to allow focus change
+                                                           # to newly opened book
         self.resizeEvent()
 
     def resizeEvent(self, event=None):