diff --git a/src/calibre/ebooks/hyphenate.py b/src/calibre/ebooks/hyphenate.py
index 2ef6ce75c8..6ae0b55886 100644
--- a/src/calibre/ebooks/hyphenate.py
+++ b/src/calibre/ebooks/hyphenate.py
@@ -82,6 +82,7 @@ class Hyphenator:
                 pieces.append('')
         return pieces
 
+
 patterns = (
 # Knuth and Liang's original hyphenation patterns from classic TeX.
 # In the public domain.
diff --git a/src/calibre/srv/tests/main.py b/src/calibre/srv/tests/main.py
index c8277cd17c..730cd9af9b 100644
--- a/src/calibre/srv/tests/main.py
+++ b/src/calibre/srv/tests/main.py
@@ -14,6 +14,7 @@ def find_tests():
     base = os.path.dirname(os.path.abspath(__file__))
     return find_tests_in_dir(base)
 
+
 if __name__ == '__main__':
     try:
         import init_calibre  # noqa
diff --git a/src/calibre/utils/formatter.py b/src/calibre/utils/formatter.py
index 5d94987a54..8a9666faad 100644
--- a/src/calibre/utils/formatter.py
+++ b/src/calibre/utils/formatter.py
@@ -306,6 +306,7 @@ class _CompileParser(_Parser):
         else:
             self.error(_('expression is not function or constant'))
 
+
 compile_counter = 0
 
 
@@ -547,6 +548,7 @@ class ValidateFormatter(TemplateFormatter):
         self.book = Metadata('')
         return self.vformat(x, [], {})
 
+
 validation_formatter = ValidateFormatter()
 
 
@@ -561,6 +563,6 @@ class EvalFormatter(TemplateFormatter):
         key = key.lower()
         return kwargs.get(key, _('No such variable ') + key)
 
+
 # DEPRECATED. This is not thread safe. Do not use.
 eval_formatter = EvalFormatter()
-
diff --git a/src/calibre/utils/threadpool.py b/src/calibre/utils/threadpool.py
index a07fd11a97..2a6109d7ae 100644
--- a/src/calibre/utils/threadpool.py
+++ b/src/calibre/utils/threadpool.py
@@ -271,6 +271,7 @@ def makeRequests(callable, args_list, callback=None, exc_callback=None):
 # USAGE EXAMPLE
 ################
 
+
 if __name__ == '__main__':
     import random
     import time