diff --git a/src/calibre/gui2/__init__.py b/src/calibre/gui2/__init__.py
index 43bbb8e65f..ecc21b9100 100644
--- a/src/calibre/gui2/__init__.py
+++ b/src/calibre/gui2/__init__.py
@@ -18,7 +18,7 @@ from PyQt5.Qt import (
     QDesktopServices, QDialog, QEvent, QFileDialog, QFileIconProvider, QFileInfo, QPalette,
     QFont, QFontDatabase, QFontInfo, QFontMetrics, QIcon, QLocale, QColor,
     QNetworkProxyFactory, QObject, QSettings, QSocketNotifier, QStringListModel, Qt,
-    QThread, QTimer, QTranslator, QUrl, pyqtSignal
+    QThread, QTimer, QTranslator, QUrl, pyqtSignal, QIODevice
 )
 from PyQt5.QtWidgets import QStyle  # Gives a nicer error message than import from Qt
 
@@ -709,7 +709,7 @@ def pixmap_to_data(pixmap, format='JPEG', quality=None):
             quality = 90
     ba = QByteArray()
     buf = QBuffer(ba)
-    buf.open(QBuffer.WriteOnly)
+    buf.open(QIODevice.OpenModeFlag.WriteOnly)
     pixmap.save(buf, format, quality=quality)
     return ba.data()
 
diff --git a/src/calibre/gui2/dbus_export/utils.py b/src/calibre/gui2/dbus_export/utils.py
index 078de65637..b4dc7c389c 100644
--- a/src/calibre/gui2/dbus_export/utils.py
+++ b/src/calibre/gui2/dbus_export/utils.py
@@ -9,7 +9,7 @@ import sys, array, re, os, errno
 
 import dbus
 
-from PyQt5.Qt import QSize, QImage, Qt, QKeySequence, QBuffer, QByteArray
+from PyQt5.Qt import QSize, QImage, Qt, QKeySequence, QBuffer, QByteArray, QIODevice
 
 from polyglot.builtins import unicode_type, iteritems
 
@@ -127,7 +127,7 @@ def icon_to_dbus_menu_icon(icon, size=32):
         return None
     ba = QByteArray()
     buf = QBuffer(ba)
-    buf.open(QBuffer.WriteOnly)
+    buf.open(QIODevice.OpenModeFlag.WriteOnly)
     icon.pixmap(32).save(buf, 'PNG')
     return dbus.ByteArray(ba)
 
diff --git a/src/calibre/gui2/library/alternate_views.py b/src/calibre/gui2/library/alternate_views.py
index 27b67acf2a..97be85729f 100644
--- a/src/calibre/gui2/library/alternate_views.py
+++ b/src/calibre/gui2/library/alternate_views.py
@@ -16,7 +16,7 @@ from PyQt5.Qt import (
     QItemSelectionModel, QListView, QMimeData, QModelIndex, QPainter, QPixmap,
     QPoint, QPropertyAnimation, QRect, QSize, QStyledItemDelegate,
     QStyleOptionViewItem, Qt, QTableView, QTimer, QToolTip, QTreeView, QUrl,
-    pyqtProperty, pyqtSignal, pyqtSlot, qBlue, qGreen, qRed
+    pyqtProperty, pyqtSignal, pyqtSlot, qBlue, qGreen, qRed, QIODevice
 )
 from textwrap import wrap
 from threading import Event, Thread
@@ -77,7 +77,7 @@ def handle_enter_press(self, ev, special_action=None, has_edit_cell=True):
 def image_to_data(image):  # {{{
     ba = QByteArray()
     buf = QBuffer(ba)
-    buf.open(QBuffer.WriteOnly)
+    buf.open(QIODevice.OpenModeFlag.WriteOnly)
     if not image.save(buf, CACHE_FORMAT):
         raise EncodeError('Failed to encode thumbnail')
     ret = ba.data()
diff --git a/src/calibre/gui2/library/views.py b/src/calibre/gui2/library/views.py
index efa333f2ad..8cb6dc6bdb 100644
--- a/src/calibre/gui2/library/views.py
+++ b/src/calibre/gui2/library/views.py
@@ -12,7 +12,7 @@ from collections import OrderedDict
 
 from PyQt5.Qt import (
     QTableView, Qt, QAbstractItemView, QMenu, pyqtSignal, QFont, QModelIndex,
-    QIcon, QItemSelection, QMimeData, QDrag, QStyle, QPoint, QUrl, QHeaderView,
+    QIcon, QItemSelection, QMimeData, QDrag, QStyle, QPoint, QUrl, QHeaderView, QEvent,
     QStyleOptionHeader, QItemSelectionModel, QSize, QFontMetrics, QApplication)
 
 from calibre.constants import islinux
@@ -213,7 +213,7 @@ class BooksView(QTableView):  # {{{
     is_library_view = True
 
     def viewportEvent(self, event):
-        if (event.type() == event.ToolTip and not gprefs['book_list_tooltips']):
+        if (event.type() == QEvent.Type.ToolTip and not gprefs['book_list_tooltips']):
             return False
         try:
             ret = self.gesture_manager.handle_event(event)
diff --git a/src/calibre/gui2/open_with.py b/src/calibre/gui2/open_with.py
index 20ebb94df0..d7263c6026 100644
--- a/src/calibre/gui2/open_with.py
+++ b/src/calibre/gui2/open_with.py
@@ -12,7 +12,7 @@ from functools import partial
 from PyQt5.Qt import (
     QAction, QBuffer, QByteArray, QIcon, QInputDialog, QKeySequence, QLabel,
     QListWidget, QListWidgetItem, QPixmap, QSize, QStackedLayout, Qt, QVBoxLayout,
-    QWidget, pyqtSignal
+    QWidget, pyqtSignal, QIODevice
 )
 from threading import Thread
 
@@ -34,7 +34,7 @@ ENTRY_ROLE = Qt.ItemDataRole.UserRole
 def pixmap_to_data(pixmap):
     ba = QByteArray()
     buf = QBuffer(ba)
-    buf.open(QBuffer.WriteOnly)
+    buf.open(QIODevice.OpenModeFlag.WriteOnly)
     pixmap.save(buf, 'PNG')
     return bytearray(ba.data())
 
diff --git a/src/calibre/gui2/tweak_book/widgets.py b/src/calibre/gui2/tweak_book/widgets.py
index 465c1ba0d3..c27328e9fe 100644
--- a/src/calibre/gui2/tweak_book/widgets.py
+++ b/src/calibre/gui2/tweak_book/widgets.py
@@ -14,7 +14,7 @@ from PyQt5.Qt import (
     QPainter, QStaticText, pyqtSignal, QTextOption, QAbstractListModel,
     QModelIndex, QStyledItemDelegate, QStyle, QCheckBox, QListView,
     QTextDocument, QSize, QComboBox, QFrame, QCursor, QGroupBox, QSplitter,
-    QPixmap, QRect, QPlainTextEdit, QMimeData, QDialog)
+    QPixmap, QRect, QPlainTextEdit, QMimeData, QDialog, QEvent)
 
 from calibre import prepare_string_for_xml, human_readable
 from calibre.constants import iswindows
@@ -1236,7 +1236,7 @@ class PlainTextEdit(QPlainTextEdit):  # {{{
 
     def event(self, ev):
         et = ev.type()
-        if et == ev.ToolTip:
+        if et == QEvent.Type.ToolTip:
             self.show_tooltip(ev)
             return True
         if et == ev.ShortcutOverride:
diff --git a/src/calibre/gui2/viewer/toc.py b/src/calibre/gui2/viewer/toc.py
index a1f2424015..991e6563f2 100644
--- a/src/calibre/gui2/viewer/toc.py
+++ b/src/calibre/gui2/viewer/toc.py
@@ -9,7 +9,7 @@ from functools import partial
 from PyQt5.Qt import (
     QApplication, QFont, QHBoxLayout, QIcon, QMenu, QModelIndex, QStandardItem,
     QStandardItemModel, QStyledItemDelegate, Qt, QToolButton, QToolTip, QTreeView,
-    QWidget, pyqtSignal
+    QWidget, pyqtSignal, QEvent
 )
 
 from calibre.gui2 import error_dialog
@@ -23,7 +23,7 @@ class Delegate(QStyledItemDelegate):
         # Show a tooltip only if the item is truncated
         if not ev or not view:
             return False
-        if ev.type() == ev.ToolTip:
+        if ev.type() == QEvent.Type.ToolTip:
             rect = view.visualRect(index)
             size = self.sizeHint(option, index)
             if rect.width() < size.width():
diff --git a/src/calibre/gui2/viewer/web_view.py b/src/calibre/gui2/viewer/web_view.py
index ee3941b2fe..45de56d44e 100644
--- a/src/calibre/gui2/viewer/web_view.py
+++ b/src/calibre/gui2/viewer/web_view.py
@@ -9,7 +9,7 @@ import sys
 from itertools import count
 from PyQt5.Qt import (
     QT_VERSION, QApplication, QBuffer, QByteArray, QFontDatabase, QFontInfo,
-    QHBoxLayout, QMimeData, QSize, Qt, QTimer, QUrl, QWidget, pyqtSignal
+    QHBoxLayout, QMimeData, QSize, Qt, QTimer, QUrl, QWidget, pyqtSignal, QIODevice
 )
 from PyQt5.QtWebEngineCore import QWebEngineUrlSchemeHandler
 from PyQt5.QtWebEngineWidgets import (
@@ -100,7 +100,7 @@ def send_reply(rq, mime_type, data):
     # make the buf a child of rq so that it is automatically deleted when
     # rq is deleted
     buf = QBuffer(parent=rq)
-    buf.open(QBuffer.WriteOnly)
+    buf.open(QIODevice.OpenModeFlag.WriteOnly)
     # we have to copy data into buf as it will be garbage
     # collected by python
     buf.write(data)
diff --git a/src/calibre/utils/img.py b/src/calibre/utils/img.py
index 74f8ce71ea..0638268666 100644
--- a/src/calibre/utils/img.py
+++ b/src/calibre/utils/img.py
@@ -13,7 +13,7 @@ from io import BytesIO
 # We use explicit module imports so tracebacks when importing are more useful
 from PyQt5.QtCore import QBuffer, QByteArray, Qt
 from PyQt5.QtGui import (
-    QColor, QImage, QImageReader, QImageWriter, QPixmap, QTransform
+    QColor, QImage, QImageReader, QImageWriter, QPixmap, QTransform, QIODevice
 )
 from threading import Thread
 
@@ -151,7 +151,7 @@ def image_and_format_from_data(data):
     ' Create an image object from the specified data which should be a bytestring and also return the format of the image '
     ba = QByteArray(data)
     buf = QBuffer(ba)
-    buf.open(QBuffer.ReadOnly)
+    buf.open(QIODevice.OpenModeFlag.ReadOnly)
     r = QImageReader(buf)
     fmt = bytes(r.format()).decode('utf-8')
     return r.read(), fmt
@@ -172,7 +172,7 @@ def image_to_data(img, compression_quality=95, fmt='JPEG', png_compression_level
     fmt = fmt.upper()
     ba = QByteArray()
     buf = QBuffer(ba)
-    buf.open(QBuffer.WriteOnly)
+    buf.open(QIODevice.OpenModeFlag.WriteOnly)
     if fmt == 'GIF':
         w = QImageWriter(buf, b'PNG')
         w.setQuality(90)
@@ -609,7 +609,7 @@ def encode_jpeg(file_path, quality=80):
         raise ValueError('%s is not a valid image file' % file_path)
     ba = QByteArray()
     buf = QBuffer(ba)
-    buf.open(QBuffer.WriteOnly)
+    buf.open(QIODevice.OpenModeFlag.WriteOnly)
     if not img.save(buf, 'PPM'):
         raise ValueError('Failed to export image to PPM')
     return run_optimizer(file_path, cmd, as_filter=True, input_data=ReadOnlyFileBuffer(ba.data()))
diff --git a/src/calibre/utils/open_with/windows.py b/src/calibre/utils/open_with/windows.py
index 9479305035..8f12e1b2a6 100644
--- a/src/calibre/utils/open_with/windows.py
+++ b/src/calibre/utils/open_with/windows.py
@@ -7,7 +7,7 @@ __copyright__ = '2015, Kovid Goyal <kovid at kovidgoyal.net>'
 
 import re
 import sys
-from PyQt5.Qt import QBuffer, QByteArray, QPixmap, Qt, QtWin
+from PyQt5.Qt import QBuffer, QByteArray, QPixmap, Qt, QtWin, QIODevice
 
 from calibre.gui2 import must_use_qt
 from calibre.utils.winreg.default_programs import split_commandline
@@ -24,7 +24,7 @@ def hicon_to_pixmap(hicon):
 def pixmap_to_data(pixmap):
     ba = QByteArray()
     buf = QBuffer(ba)
-    buf.open(QBuffer.WriteOnly)
+    buf.open(QIODevice.OpenModeFlag.WriteOnly)
     pixmap.save(buf, 'PNG')
     return bytes(bytearray(ba.data()))
 
diff --git a/src/calibre/utils/wmf/__init__.py b/src/calibre/utils/wmf/__init__.py
index 65c0e05acd..238c520a16 100644
--- a/src/calibre/utils/wmf/__init__.py
+++ b/src/calibre/utils/wmf/__init__.py
@@ -61,12 +61,12 @@ def create_bmp_from_dib(raw):
 
 
 def to_png(bmp):
-    from PyQt5.Qt import QImage, QByteArray, QBuffer
+    from PyQt5.Qt import QImage, QByteArray, QBuffer, QIODevice
     i = QImage()
     if not i.loadFromData(bmp):
         raise ValueError('Invalid image data')
     ba = QByteArray()
     buf = QBuffer(ba)
-    buf.open(QBuffer.WriteOnly)
+    buf.open(QIODevice.OpenModeFlag.WriteOnly)
     i.save(buf, 'png')
     return ba.data()