diff --git a/cps/__init__.py b/cps/__init__.py
index 26750d1a..d26c3cdc 100755
--- a/cps/__init__.py
+++ b/cps/__init__.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
 #  This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)
@@ -134,8 +133,7 @@ def get_locale():
 @babel.timezoneselector
 def get_timezone():
     user = getattr(g, 'user', None)
-    if user is not None:
-        return user.timezone
+    return user.timezone if user else None
 
 from .updater import Updater
 updater_thread = Updater()
diff --git a/cps/constants.py b/cps/constants.py
index 2bedb282..9d4938b2 100644
--- a/cps/constants.py
+++ b/cps/constants.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
 #   This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)
diff --git a/cps/db.py b/cps/db.py
index 1ed56234..b9853896 100755
--- a/cps/db.py
+++ b/cps/db.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
 #  This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)
@@ -418,7 +417,7 @@ def dispose():
 
     for attr in list(Books.__dict__.keys()):
         if attr.startswith("custom_column_"):
-            delattr(Books, attr)
+            setattr(Books, attr, None)
 
     for db_class in cc_classes.values():
         Base.metadata.remove(db_class.__table__)
diff --git a/cps/editbooks.py b/cps/editbooks.py
index 8851a0d8..2da9991f 100644
--- a/cps/editbooks.py
+++ b/cps/editbooks.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
 #  This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)
@@ -301,7 +300,7 @@ def edit_cc_data(book_id, book, to_save):
                     # remove old cc_val
                     del_cc = getattr(book, cc_string)[0]
                     getattr(book, cc_string).remove(del_cc)
-                    if len(del_cc.books) == 0:
+                    if not del_cc.books or len(del_cc.books) == 0:
                         db.session.delete(del_cc)
         else:
             input_tags = to_save[cc_string].split(',')
diff --git a/cps/helper.py b/cps/helper.py
index d7308d04..c94093db 100644
--- a/cps/helper.py
+++ b/cps/helper.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
 #  This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)
diff --git a/cps/worker.py b/cps/worker.py
index 37212873..9744b91f 100644
--- a/cps/worker.py
+++ b/cps/worker.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
 #  This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)