diff --git a/lector/__main__.py b/lector/__main__.py
index 5cafb64..94d732d 100755
--- a/lector/__main__.py
+++ b/lector/__main__.py
@@ -17,6 +17,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
+import gc
 import sys
 import hashlib
 import pathlib
@@ -526,7 +527,7 @@ class MainUI(QtWidgets.QMainWindow, mainwindow.Ui_MainWindow):
 
             # Update the database in the background
             self.thread = BackGroundBookDeletion(
-                delete_hashes, self.database_path, self)
+                delete_hashes, self.database_path)
             self.thread.finished.connect(self.move_on)
             self.thread.start()
 
@@ -647,7 +648,10 @@ class MainUI(QtWidgets.QMainWindow, mainwindow.Ui_MainWindow):
         self.thread.start()
 
         self.tabWidget.widget(tab_index).update_last_accessed_time()
-        self.tabWidget.removeTab(tab_index)
+
+        self.tabWidget.widget(tab_index).deleteLater()
+        self.tabWidget.widget(tab_index).setParent(None)
+        gc.collect()
 
     def set_toc_position(self, event=None):
         current_tab = self.tabWidget.widget(self.tabWidget.currentIndex())
@@ -773,7 +777,7 @@ class MainUI(QtWidgets.QMainWindow, mainwindow.Ui_MainWindow):
             # New tabs are created here
             # Initial position adjustment is carried out by the tab itself
             file_data = contents[i]
-            Tab(file_data, self.tabWidget)
+            Tab(file_data, self)
 
         if self.settings['last_open_tab'] == 'library':
             self.tabWidget.setCurrentIndex(0)
diff --git a/lector/settingsdialog.py b/lector/settingsdialog.py
index f701527..83f146f 100644
--- a/lector/settingsdialog.py
+++ b/lector/settingsdialog.py
@@ -32,7 +32,7 @@ from resources import settingswindow
 
 
 class SettingsUI(QtWidgets.QDialog, settingswindow.Ui_Dialog):
-    def __init__(self, parent):
+    def __init__(self, parent=None):
         super(SettingsUI, self).__init__()
         self.setupUi(self)
         self._translate = QtCore.QCoreApplication.translate
@@ -216,7 +216,7 @@ class SettingsUI(QtWidgets.QDialog, settingswindow.Ui_Dialog):
         # Traverse directories looking for files
         self.parent.statusMessage.setText(
             self._translate('SettingsUI', 'Checking library folders'))
-        self.thread = BackGroundBookSearch(data_pairs, self)
+        self.thread = BackGroundBookSearch(data_pairs)
         self.thread.finished.connect(self.finished_iterating)
         self.thread.start()
 
diff --git a/lector/threaded.py b/lector/threaded.py
index d272ccd..c0fa2e1 100644
--- a/lector/threaded.py
+++ b/lector/threaded.py
@@ -44,12 +44,12 @@ class BackGroundTabUpdate(QtCore.QThread):
 
 
 class BackGroundBookAddition(QtCore.QThread):
-    def __init__(self, file_list, database_path, addition_mode, parent=None):
+    def __init__(self, file_list, database_path, addition_mode, main_window, parent=None):
         super(BackGroundBookAddition, self).__init__(parent)
         self.file_list = file_list
-        self.parent = parent
         self.database_path = database_path
         self.addition_mode = addition_mode
+        self.main_window = main_window
 
         self.prune_required = True
         if self.addition_mode == 'manual':
@@ -60,21 +60,20 @@ class BackGroundBookAddition(QtCore.QThread):
             self.file_list,
             ('addition', self.addition_mode),
             self.database_path,
-            self.parent.settings['auto_tags'],
-            self.parent.temp_dir.path())
+            self.main_window.settings['auto_tags'],
+            self.main_window.temp_dir.path())
 
         parsed_books = books.initiate_threads()
-        self.parent.lib_ref.generate_model('addition', parsed_books, False)
+        self.main_window.lib_ref.generate_model('addition', parsed_books, False)
         database.DatabaseFunctions(self.database_path).add_to_database(parsed_books)
 
         if self.prune_required:
-            self.parent.lib_ref.prune_models(self.file_list)
+            self.main_window.lib_ref.prune_models(self.file_list)
 
 
 class BackGroundBookDeletion(QtCore.QThread):
     def __init__(self, hash_list, database_path, parent=None):
         super(BackGroundBookDeletion, self).__init__(parent)
-        self.parent = parent
         self.hash_list = hash_list
         self.database_path = database_path
 
@@ -86,7 +85,6 @@ class BackGroundBookDeletion(QtCore.QThread):
 class BackGroundBookSearch(QtCore.QThread):
     def __init__(self, data_list, parent=None):
         super(BackGroundBookSearch, self).__init__(parent)
-        self.parent = parent
         self.valid_files = []
 
         # Filter for checked directories
diff --git a/lector/widgets.py b/lector/widgets.py
index ed9d5cd..41525e7 100644
--- a/lector/widgets.py
+++ b/lector/widgets.py
@@ -41,15 +41,16 @@ from lector.sorter import resize_image
 
 
 class Tab(QtWidgets.QWidget):
-    def __init__(self, metadata, parent=None):
+    def __init__(self, metadata, main_window, parent=None):
         super(Tab, self).__init__(parent)
         self._translate = QtCore.QCoreApplication.translate
 
-        self.parent = parent
+        self.setAttribute(QtCore.Qt.WA_DeleteOnClose)
+
+        self.main_window = main_window
         self.metadata = metadata  # Save progress data into this dictionary
         self.are_we_doing_images_only = self.metadata['images_only']
         self.is_fullscreen = False
-        self.main_window = self.window()
 
         self.masterLayout = QtWidgets.QHBoxLayout(self)
         self.masterLayout.setContentsMargins(0, 0, 0, 0)
@@ -152,7 +153,7 @@ class Tab(QtWidgets.QWidget):
         self.horzLayout.addWidget(self.contentView)
         self.horzLayout.addWidget(self.dockWidget)
         title = self.metadata['title']
-        self.parent.addTab(self, title)
+        self.main_window.tabWidget.addTab(self, title)
 
         # Hide mouse cursor timer
         self.mouse_hide_timer = QtCore.QTimer()