diff --git a/ansibledoctor/Exception.py b/ansibledoctor/Exception.py
index 676afb6..0ff5156 100644
--- a/ansibledoctor/Exception.py
+++ b/ansibledoctor/Exception.py
@@ -6,7 +6,7 @@ class DoctorError(Exception):
     """Generic exception class for ansible-doctor."""
 
     def __init__(self, msg, original_exception=""):
-        super(DoctorError, self).__init__(msg + ("\n%s" % original_exception))
+        super(DoctorError, self).__init__("{msg}\n{org}".format(msg=msg, org=original_exception))
         self.original_exception = original_exception
 
 
diff --git a/dev-requirements.txt b/dev-requirements.txt
index 8a7cdfe..1d053e7 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -8,6 +8,7 @@ flake8-isort
 flake8-logging-format
 flake8-polyfill
 flake8-quotes
+flake8-pep3101
 flake8-eradicate; python_version >= "3.6"
 pep8-naming
 wheel