diff --git a/recipes/mediapart.recipe b/recipes/mediapart.recipe
index 015a5c69fb..e6c2ac4b41 100644
--- a/recipes/mediapart.recipe
+++ b/recipes/mediapart.recipe
@@ -253,7 +253,7 @@ class Mediapart(BasicNewsRecipe):
         '''
         Create a generic cover for recipes that don't have a cover
         '''
-        from PyQt5.Qt import QImage, QPainter, QPen, Qt, QFont, QRect
+        from qt.core import QImage, QPainter, QPen, Qt, QFont, QRect
         from calibre.gui2 import ensure_app, load_builtin_fonts, pixmap_to_data
 
         def init_environment():
diff --git a/setup/build.py b/setup/build.py
index aa1013c188..25a9ca1ea3 100644
--- a/setup/build.py
+++ b/setup/build.py
@@ -530,7 +530,7 @@ build-backend = "sipbuild.api"
 
 [tool.sip.metadata]
 name = "{ext.name}"
-requires-dist = "PyQt5 (>=5.15)"
+requires-dist = "PyQt6 (>=6.2.1)"
 
 [tool.sip]
 project-factory = "pyqtbuild:PyQtProject"
diff --git a/setup/build_environment.py b/setup/build_environment.py
index fb5135612e..70b497cd11 100644
--- a/setup/build_environment.py
+++ b/setup/build_environment.py
@@ -15,9 +15,9 @@ NMAKE = RC = msvc = MT = win_inc = win_lib = win_cc = win_ld = None
 
 @lru_cache(maxsize=2)
 def pyqt_sip_abi_version():
-    import PyQt5
-    if getattr(PyQt5, '__file__', None):
-        bindings_path = os.path.join(os.path.dirname(PyQt5.__file__), 'bindings', 'QtCore', 'QtCore.toml')
+    import PyQt6
+    if getattr(PyQt6, '__file__', None):
+        bindings_path = os.path.join(os.path.dirname(PyQt6.__file__), 'bindings', 'QtCore', 'QtCore.toml')
         if os.path.exists(bindings_path):
             with open(bindings_path) as f:
                 raw = f.read()
@@ -52,7 +52,7 @@ if iswindows:
             os.environ[key] = env[key]
 
 QMAKE = 'qmake'
-for x in ('qmake-qt5', 'qt5-qmake', 'qmake'):
+for x in ('qmake6', 'qmake-qt6', 'qt6-qmake', 'qmake'):
     q = shutil.which(x)
     if q:
         QMAKE = q
diff --git a/src/calibre/gui2/dialogs/catalog.py b/src/calibre/gui2/dialogs/catalog.py
index 7b8b06f808..cbc19838b7 100644
--- a/src/calibre/gui2/dialogs/catalog.py
+++ b/src/calibre/gui2/dialogs/catalog.py
@@ -25,7 +25,7 @@ class Catalog(QDialog, Ui_Dialog):
 
     def __init__(self, parent, dbspec, ids, db):
         import re
-        from PyQt5.uic import compileUi
+        from PyQt6.uic import compileUi
 
         from calibre import prints as info
 
diff --git a/src/calibre/gui2/widgets.py b/src/calibre/gui2/widgets.py
index ba9caddc77..9995c17109 100644
--- a/src/calibre/gui2/widgets.py
+++ b/src/calibre/gui2/widgets.py
@@ -867,7 +867,7 @@ class PythonHighlighter(QSyntaxHighlighter):  # {{{
                 r"|\b[+-]?[0-9]+(?:\.[0-9]+)?(?:[eE][+-]?[0-9]+)?\b"),
                 "number")
         a(re.compile(
-                r"\bPyQt5\b|\bQt?[A-Z][a-z]\w+\b"), "pyqt")
+                r"\bPyQt6\b|\bQt?[A-Z][a-z]\w+\b"), "pyqt")
         a(re.compile(r"\b@\w+\b"), "decorator")
         stringRe = re.compile(r"""(?:'[^']*?'|"[^"]*?")""")
         a(stringRe, "string")
diff --git a/src/calibre/utils/config_base.py b/src/calibre/utils/config_base.py
index 880aa7f854..04c4266f07 100644
--- a/src/calibre/utils/config_base.py
+++ b/src/calibre/utils/config_base.py
@@ -28,7 +28,7 @@ def parse_old_style(src):
     try:
         if not isinstance(src, str):
             src = src.decode('utf-8')
-        src = src.replace('PyQt%d.QtCore' % 4, 'PyQt5.QtCore')
+        src = re.sub(r'PyQt(?:4|5).QtCore', r'PyQt6.QtCore', src)
         src = re.sub(r'cPickle\.loads\(([\'"])', r'cPickle.loads(b\1', src)
         exec(src, options)
     except Exception as err:
diff --git a/src/calibre/utils/rapydscript.py b/src/calibre/utils/rapydscript.py
index 6fcd8ea274..f55dbabf1c 100644
--- a/src/calibre/utils/rapydscript.py
+++ b/src/calibre/utils/rapydscript.py
@@ -205,7 +205,7 @@ def ok_to_import_webengine():
     from qt.core import QApplication
     if QApplication.instance() is None:
         return True
-    if 'PyQt5.QtWebEngineWidgets' in sys.modules:
+    if 'PyQt6.QtWebEngineWidgets' in sys.modules:
         return True
     return False