diff --git a/recipes/daum_net.recipe b/recipes/daum_net.recipe
index f840c15254..c1adb61c21 100644
--- a/recipes/daum_net.recipe
+++ b/recipes/daum_net.recipe
@@ -61,7 +61,7 @@ class MediaDaumRecipe(BasicNewsRecipe):
             lambda match: '<em>'),
         (re.compile(r'<i>(<br[^>]*>[ \t\r\n]*)*', re.DOTALL | re.IGNORECASE),
             lambda match: '<i>'),
-        (re.compile(u'(<br[^>]*>[ \t\r\n]*)*(\u25B6|\u25CF|\u261E|\u24D2|\(c\))*\[[^\]]*(\u24D2|\(c\)|\uAE30\uC0AC|\uC778\uAE30[^\]]*\uB274\uC2A4)[^\]]*\].*</div>', re.DOTALL | re.IGNORECASE),  # noqa: E501, W605
+        (re.compile(u'(<br[^>]*>[ \t\r\n]*)*(\u25B6|\u25CF|\u261E|\u24D2|\\(c\\))*\\[[^\\]]*(\u24D2|\\(c\\)|\uAE30\uC0AC|\uC778\uAE30[^\\]]*\uB274\uC2A4)[^\\]]*\\].*</div>', re.DOTALL | re.IGNORECASE),  # noqa: E501
             lambda match: '</div>'),
     ]
 
diff --git a/recipes/nytimes.recipe b/recipes/nytimes.recipe
index 0ab2454b53..fb42463da6 100644
--- a/recipes/nytimes.recipe
+++ b/recipes/nytimes.recipe
@@ -7,7 +7,6 @@ from __future__ import absolute_import, division, print_function, unicode_litera
 import datetime
 import json
 import re
-from pprint import pprint  # noqa: F401
 
 from calibre import strftime
 from calibre.ebooks.BeautifulSoup import Tag
diff --git a/recipes/nytimes_sub.recipe b/recipes/nytimes_sub.recipe
index cbed02b28b..d069d1545d 100644
--- a/recipes/nytimes_sub.recipe
+++ b/recipes/nytimes_sub.recipe
@@ -7,7 +7,6 @@ from __future__ import absolute_import, division, print_function, unicode_litera
 import datetime
 import json
 import re
-from pprint import pprint  # noqa: F401
 
 from calibre import strftime
 from calibre.ebooks.BeautifulSoup import Tag
diff --git a/src/calibre/customize/builtins.py b/src/calibre/customize/builtins.py
index 491400347c..ceac30d58c 100644
--- a/src/calibre/customize/builtins.py
+++ b/src/calibre/customize/builtins.py
@@ -1997,7 +1997,7 @@ if __name__ == '__main__':
     try:
         subprocess.check_call(['python', '-c', textwrap.dedent(
         '''
-        import time, sys, init_calibre
+        import time, sys, init_calibre  # noqa: F401
         st = time.time()
         import calibre.customize.builtins
         t = time.time() - st
diff --git a/src/calibre/ebooks/conversion/plugins/pdf_output.py b/src/calibre/ebooks/conversion/plugins/pdf_output.py
index a1dcee7f18..4bdbf3c00b 100644
--- a/src/calibre/ebooks/conversion/plugins/pdf_output.py
+++ b/src/calibre/ebooks/conversion/plugins/pdf_output.py
@@ -151,9 +151,10 @@ class PDFOutput(OutputFormatPlugin):
         # Ensure Qt is setup to be used with WebEngine
         # specialize_options is called early enough in the pipeline
         # that hopefully no Qt application has been constructed as yet
-        from qt.webengine import QWebEnginePage  # noqa: I001, F401
+        from qt.webengine import QWebEnginePage  # noqa: F401
+
         from calibre.gui2 import must_use_qt
-        from calibre.utils.webengine import setup_fake_protocol, setup_default_profile
+        from calibre.utils.webengine import setup_default_profile, setup_fake_protocol
         setup_fake_protocol()
         must_use_qt()
         setup_default_profile()
diff --git a/src/calibre/gui2/email.py b/src/calibre/gui2/email.py
index e66ecfa8ad..17ddbcabe9 100644
--- a/src/calibre/gui2/email.py
+++ b/src/calibre/gui2/email.py
@@ -543,5 +543,5 @@ class EmailMixin:  # {{{
 
 if __name__ == '__main__':
     from qt.core import QApplication
-    app = QApplication([])
+    app = QApplication([])  # noqa: F841
     print(select_recipients())
diff --git a/src/calibre/gui2/preferences/texture_chooser.py b/src/calibre/gui2/preferences/texture_chooser.py
index dc94c617dd..a0f1ea55ca 100644
--- a/src/calibre/gui2/preferences/texture_chooser.py
+++ b/src/calibre/gui2/preferences/texture_chooser.py
@@ -165,7 +165,7 @@ class TextureChooser(QDialog):
 
 
 if __name__ == '__main__':
-    app = QApplication([])
+    app = QApplication([])  # noqa: F841
     d = TextureChooser()
     d.exec()
     print(d.texture)
diff --git a/src/calibre/gui2/tweak_book/check.py b/src/calibre/gui2/tweak_book/check.py
index ad4a5f6e5c..e34d04ccf3 100644
--- a/src/calibre/gui2/tweak_book/check.py
+++ b/src/calibre/gui2/tweak_book/check.py
@@ -271,7 +271,7 @@ class Check(QSplitter):
 def main():
     from calibre.gui2 import Application
     from calibre.gui2.tweak_book.boss import get_container
-    app = Application([])
+    app = Application([])  # noqa: F841
     path = sys.argv[-1]
     container = get_container(path)
     d = Check()
diff --git a/src/calibre/gui2/tweak_book/diff/main.py b/src/calibre/gui2/tweak_book/diff/main.py
index a872ee0a73..ae9bbd1675 100644
--- a/src/calibre/gui2/tweak_book/diff/main.py
+++ b/src/calibre/gui2/tweak_book/diff/main.py
@@ -519,7 +519,7 @@ def main(args=sys.argv):
         attr = 'ebook_diff'
     else:
         attr = 'file_diff'
-    app = Application([])
+    app = Application([])  # noqa: F841
     d = Diff(show_as_window=True)
     func = getattr(d, attr)
     QTimer.singleShot(0, lambda : func(left, right))
diff --git a/src/calibre/gui2/tweak_book/editor/insert_resource.py b/src/calibre/gui2/tweak_book/editor/insert_resource.py
index 2971b5ba9e..ed6f2c66be 100644
--- a/src/calibre/gui2/tweak_book/editor/insert_resource.py
+++ b/src/calibre/gui2/tweak_book/editor/insert_resource.py
@@ -516,7 +516,7 @@ class NewBook(Dialog):  # {{{
 
 
 if __name__ == '__main__':
-    app = QApplication([])
+    app = QApplication([])  # noqa: F841
     from calibre.gui2.tweak_book import set_current_container
     from calibre.gui2.tweak_book.boss import get_container
     set_current_container(get_container(sys.argv[-1]))
diff --git a/src/calibre/ptempfile.py b/src/calibre/ptempfile.py
index 78722c339c..3fb5f87783 100644
--- a/src/calibre/ptempfile.py
+++ b/src/calibre/ptempfile.py
@@ -38,7 +38,7 @@ def determined_remove_dir(x):
             shutil.rmtree(x)
             return
         except:
-            import os
+            import os  # noqa
             if os.path.exists(x):
                 # In case some other program has one of the temp files open.
                 import time
diff --git a/src/calibre/utils/fonts/sfnt/subset.py b/src/calibre/utils/fonts/sfnt/subset.py
index 2377467ba5..e3fedfe20b 100644
--- a/src/calibre/utils/fonts/sfnt/subset.py
+++ b/src/calibre/utils/fonts/sfnt/subset.py
@@ -300,8 +300,7 @@ def main(args):
 
 if __name__ == '__main__':
     try:
-        import init_calibre
-        init_calibre
+        import init_calibre  # noqa: F401
     except ImportError:
         pass
     import sys
diff --git a/src/calibre/utils/ipython.py b/src/calibre/utils/ipython.py
index 5e18af640e..1efa73232b 100644
--- a/src/calibre/utils/ipython.py
+++ b/src/calibre/utils/ipython.py
@@ -121,7 +121,7 @@ history_length(2000) #value of -1 means no limit
         import atexit
         import readline
 
-        import pyreadline.unicode_helper
+        import pyreadline.unicode_helper  # noqa: F401
         # Normally the codepage for pyreadline is set to be sys.stdout.encoding
         # if you need to change this uncomment the following line
         # pyreadline.unicode_helper.pyreadline_codepage="utf8"
@@ -172,8 +172,7 @@ def simple_repl(user_ns={}):
         setup_pyreadline()
     else:
         try:
-            import rlcompleter  # noqa: I001, F401
-            import readline
+            import readline, rlcompleter  # noqa: I001, E401, F401
             readline.parse_and_bind("tab: complete")
         except ImportError:
             pass