diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index e5403cf..f64c046 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9]
+        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9, '3.10']
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python ${{ matrix.python-version }}
diff --git a/lintly/backends/base.py b/lintly/backends/base.py
index 7f87f55..4ee27ee 100644
--- a/lintly/backends/base.py
+++ b/lintly/backends/base.py
@@ -39,7 +39,7 @@ def get_pr_diff(self, pr):
         """
         raise NotImplementedError
 
-    def create_pull_request_review(self, pr, patch, all_violations, pr_review_action):
+    def create_pull_request_review(self, pr, patch, all_violations, pr_review_action, has_body):
         """
         Creates a pull request review for the given build.
         """
diff --git a/lintly/backends/dummy.py b/lintly/backends/dummy.py
index 588ea9d..f02e7bb 100644
--- a/lintly/backends/dummy.py
+++ b/lintly/backends/dummy.py
@@ -17,7 +17,7 @@ def create_pull_request_comment(self, pr, comment):
     def delete_pull_request_comments(self, pr):
         pass
 
-    def create_pull_request_review(self, pr, patch, all_violations, pr_review_action):
+    def create_pull_request_review(self, pr, patch, all_violations, pr_review_action, has_body):
         pass
 
     def delete_pull_request_review_comments(self, pr):
diff --git a/lintly/backends/github.py b/lintly/backends/github.py
index b5579cf..1798137 100644
--- a/lintly/backends/github.py
+++ b/lintly/backends/github.py
@@ -7,7 +7,7 @@
 
 from github import GithubException, UnknownObjectException, Github
 
-from lintly.constants import LINTLY_IDENTIFIER
+from lintly.config import Config
 from lintly.formatters import (
     build_pr_review_line_comment,
     build_pr_review_body,
@@ -124,7 +124,7 @@ def __init__(self, token, project, context):
         self.context = context
 
     def _should_delete_comment(self, comment):
-        return LINTLY_IDENTIFIER in comment.body
+        return Config.LINTLY_IDENTIFIER in comment.body
 
     @translate_github_exception
     def get_pull_request(self, pr):
@@ -180,7 +180,7 @@ def _get_event(self, review_action):
         elif review_action == ACTION_REVIEW_APPROVE:
             return 'APPROVE'
 
-    def create_pull_request_review(self, pr, patch, all_violations, pr_review_action):
+    def create_pull_request_review(self, pr, patch, all_violations, pr_review_action, has_body):
         comments = []
         for file_path in all_violations:
             violations = all_violations[file_path]
@@ -209,10 +209,11 @@ def create_pull_request_review(self, pr, patch, all_violations, pr_review_action
             # there are no pending comments to add then we send the request
             if len(comments_batch) == GITHUB_PULL_REQUEST_COMMENT_LIMIT or not comments:
                 data = {
-                    'body': build_pr_review_body(all_violations),
                     'event': self._get_event(pr_review_action),
                     'comments': comments_batch,
                 }
+                if has_body:
+                    data['body'] = build_pr_review_body(all_violations)
 
                 url = '/repos/{owner}/{repo_name}/pulls/{pr_number}/reviews'.format(
                     owner=self.project.owner_login,
diff --git a/lintly/backends/gitlab.py b/lintly/backends/gitlab.py
index 4d5e068..37769e4 100644
--- a/lintly/backends/gitlab.py
+++ b/lintly/backends/gitlab.py
@@ -7,7 +7,7 @@
 import gitlab
 import requests
 
-from lintly.constants import LINTLY_IDENTIFIER
+from lintly.config import Config
 
 from .base import BaseGitBackend
 from .errors import (
@@ -136,14 +136,14 @@ def delete_pull_request_comments(self, pr):
         mr = project.mergerequests.list(iid=pr)[0]
         client = GitLabAPIClient(self.token, self.user, self.project)
         for note in mr.notes.list(all=True, per_page=DEFAULT_PER_PAGE):
-            if LINTLY_IDENTIFIER in note.body:
+            if Config.LINTLY_IDENTIFIER in note.body:
                 url = '/projects/{project_id}/merge_requests/{mr_id}/notes/{note_id}'.format(
                     project_id=project.id, mr_id=mr.id, note_id=note.id
                 )
                 client.delete(url)
 
     @translate_gitlab_exception
-    def create_pull_request_review(self, pr, patch, all_violations, pr_review_action):
+    def create_pull_request_review(self, pr, patch, all_violations, pr_review_action, has_body):
         raise NotSupportedError()
 
     @translate_gitlab_exception
diff --git a/lintly/builds.py b/lintly/builds.py
index ebc603d..ace490b 100644
--- a/lintly/builds.py
+++ b/lintly/builds.py
@@ -164,7 +164,8 @@ def submit_pr_review(self, patch, pr_review_action):
                 self.config.pr,
                 patch,
                 self._diff_violations,
-                pr_review_action
+                pr_review_action,
+                self.config.review_body
             )
             post_pr_comment = False
         except GitClientError as e:
diff --git a/lintly/cli.py b/lintly/cli.py
index cded503..e50ced2 100644
--- a/lintly/cli.py
+++ b/lintly/cli.py
@@ -55,6 +55,16 @@
 @click.option('--log',
               is_flag=True,
               help='Send Lintly debug logs to the console. Default false')
+@click.option('--review-body/--no-review-body',
+              default=True,
+              help=('Whether Lintly should post a PR review with a body. '
+                    'The body is not removed after a re-run.'))
+@click.option('--comment-tag',
+              default='',
+              help='A tag used to identify comments from a previous run that should be deleted')
+@click.option('--base-dir',
+              default='.',
+              help='The base git directory')
 @click.option('--exit-zero/--no-exit-zero', default=False,
               help=('Whether Lintly should exit with error code indicating '
                     'amount of violations or not. Default false'))
diff --git a/lintly/config.py b/lintly/config.py
index ae6eac1..174646c 100644
--- a/lintly/config.py
+++ b/lintly/config.py
@@ -7,8 +7,14 @@
 class Config(object):
     """A Config object that knows how to return configuration from the CLI or Continuous Integration services"""
 
+    LINTLY_IDENTIFIER = '<!-- Automatically posted by Lintly -->'
+    BASE_DIR = '.'
+
     def __init__(self, cli_config):
         self.cli_config = cli_config
+        if self.comment_tag:
+            type(self).LINTLY_IDENTIFIER = '(%s)%s' % (self.comment_tag, type(self).LINTLY_IDENTIFIER)
+        type(self).BASE_DIR = self.base_dir
 
     def as_dict(self):
         return {
@@ -21,6 +27,9 @@ def as_dict(self):
             'post_status': self.post_status,
             'request_changes': self.request_changes,
             'github_check_run_id': self.github_check_run_id,
+            'review_body': self.review_body,
+            'comment_tag': self.comment_tag,
+            'base_dir': self.base_dir,
         }
 
     @property
@@ -59,6 +68,18 @@ def post_status(self):
     def request_changes(self):
         return self.cli_config['request_changes']
 
+    @property
+    def review_body(self):
+        return self.cli_config['review_body']
+
+    @property
+    def comment_tag(self):
+        return self.cli_config['comment_tag']
+
+    @property
+    def base_dir(self):
+        return self.cli_config['base_dir']
+
     @property
     def github_check_run_id(self):
         """The Check Run ID from GitHub Actions.
diff --git a/lintly/constants.py b/lintly/constants.py
index b3a0583..5c3fc42 100644
--- a/lintly/constants.py
+++ b/lintly/constants.py
@@ -1,11 +1,6 @@
 FAIL_ON_ANY = 'any'
 FAIL_ON_NEW = 'new'
 
-# Identifies that a comment came from Lintly. This is used to aid in automatically
-# deleting old PR comments/reviews. This is valid Markdown that is hidden from
-# users in GitHub and GitLab.
-LINTLY_IDENTIFIER = '<!-- Automatically posted by Lintly -->'
-
 # These constants define the actions that lintly might take against a PR concerning reviews, ie.
 # not the commit status
 ACTION_REVIEW_USE_CHECKS = 'use_checks'
diff --git a/lintly/formatters.py b/lintly/formatters.py
index fdeb274..88f81a5 100644
--- a/lintly/formatters.py
+++ b/lintly/formatters.py
@@ -5,7 +5,7 @@
 
 from jinja2 import Environment, FileSystemLoader
 
-from .constants import LINTLY_IDENTIFIER
+from .config import Config
 
 
 TEMPLATES_PATH = os.path.join(os.path.dirname(__file__), 'templates')
@@ -23,7 +23,7 @@ def build_pr_comment(config, violations):
     :return: The comment
     """
     template = env.get_template('pr_comment.txt')
-    return template.render(violations=violations, LINTLY_IDENTIFIER=LINTLY_IDENTIFIER)
+    return template.render(violations=violations, LINTLY_IDENTIFIER=Config.LINTLY_IDENTIFIER)
 
 
 def build_pr_review_line_comment(violation):
@@ -32,7 +32,7 @@ def build_pr_review_line_comment(violation):
     :return: The comment
     """
     template = env.get_template('pr_review_line_comment.txt')
-    return template.render(violation=violation, LINTLY_IDENTIFIER=LINTLY_IDENTIFIER)
+    return template.render(violation=violation, LINTLY_IDENTIFIER=Config.LINTLY_IDENTIFIER)
 
 
 def build_check_line_comment(violation):
@@ -42,4 +42,4 @@ def build_check_line_comment(violation):
 
 def build_pr_review_body(violations):
     template = env.get_template('pr_review_body.txt')
-    return template.render(violations=violations, LINTLY_IDENTIFIER=LINTLY_IDENTIFIER)
+    return template.render(violations=violations, LINTLY_IDENTIFIER=Config.LINTLY_IDENTIFIER)
diff --git a/lintly/parsers.py b/lintly/parsers.py
index d34bf5e..3ba3269 100644
--- a/lintly/parsers.py
+++ b/lintly/parsers.py
@@ -8,6 +8,7 @@
 import re
 
 from .violations import Violation
+from .config import Config
 
 
 class BaseLintParser(object):
@@ -15,15 +16,15 @@ class BaseLintParser(object):
     def parse_violations(self, output):
         raise NotImplementedError
 
-    def _get_working_dir(self):
-        return os.getcwd()
-
     def _normalize_path(self, path):
         """
         Normalizes a file path so that it returns a path relative to the root repo directory.
         """
         norm_path = os.path.normpath(path)
-        return os.path.relpath(norm_path, start=self._get_working_dir())
+        rel_path = os.path.relpath(norm_path, start=Config.BASE_DIR)
+        if os.name == 'nt':
+            rel_path = rel_path.replace('\\', '/')
+        return rel_path
 
 
 class LineRegexParser(BaseLintParser):
@@ -58,11 +59,12 @@ def parse_violations(self, output):
 
             path = self._normalize_path(match.group('path'))
 
+            groups = match.groupdict()
             violation = Violation(
-                line=int(match.group('line')),
-                column=int(match.group('column')),
-                code=match.group('code'),
-                message=match.group('message')
+                line=int(groups.get('line') or 1),
+                column=int(groups.get('column') or 1),
+                code=(groups.get('code') or '[empty]').strip(),
+                message=(groups.get('message') or '[empty]').strip()
             )
 
             violations[path].append(violation)
@@ -296,4 +298,8 @@ def parse_violations(self, output):
 
     # cfn-nag JSON output
     'cfn-nag': CfnNagParser(),
+
+    # Mypy formatter
+    'mypy': LineRegexParser(r'^(?P<path>.*\.py):(?:(?P<line>\d*):)?(?:(?P<column>\d*):)? [^:]*: '
+                            r'(?P<message>.*?)(?:\[(?P<code>\S*)\])?$'),
 }
diff --git a/requirements.txt b/requirements.txt
index 0195ca8..534dd82 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,12 +1,12 @@
-Jinja2<3.0
+Jinja2<4.0
 PyGithub<2.0
 cached-property<2.0
 ci-py
-click<7.0
+click<9.0
 codecov
 coverage
 flake8
 mock
 pytest
-python-gitlab<2.0
+python-gitlab<4.0
 tox
diff --git a/setup.py b/setup.py
index 03ddd4b..460bc7a 100644
--- a/setup.py
+++ b/setup.py
@@ -8,10 +8,10 @@
 dependencies = [
     'ci-py',
     'cached-property<2.0',
-    'click<8.0',
-    'Jinja2<3.0',
+    'click<9.0',
+    'Jinja2<4.0',
     'PyGithub<2.0',
-    'python-gitlab<2.0',
+    'python-gitlab<4.0',
     'six',
 ]
 
diff --git a/tests/test_builds.py b/tests/test_builds.py
index d9d844f..598d279 100644
--- a/tests/test_builds.py
+++ b/tests/test_builds.py
@@ -31,6 +31,8 @@ def config(format_and_context):
         "commit_sha": "xyz123notarealsha",
         "context": format_and_context[1],
         "post_status": True,
+        "comment_tag": "",
+        'base_dir': ".",
     }
 
     return Config(cli_config)
diff --git a/tests/test_parsers.py b/tests/test_parsers.py
index 3e7a479..1131410 100644
--- a/tests/test_parsers.py
+++ b/tests/test_parsers.py
@@ -2,12 +2,8 @@
 import os
 import unittest
 
-try:
-    from unittest.mock import patch
-except ImportError:
-    from mock import patch
-
 from lintly.parsers import PARSERS
+from lintly.config import Config
 
 
 class ParserTestCaseMixin(object):
@@ -57,6 +53,7 @@ def load_linter_output(file_name):
             return linter_output.read()
 
     def setUp(self):
+        Config.BASE_DIR = '.'
         self.linter_output = self.load_linter_output(self.linter_output_file_name)
 
     def test_parse_violations(self):
@@ -137,8 +134,8 @@ class ESLintParserTestCase(ParserTestCaseMixin, unittest.TestCase):
         ]
     }
 
-    @patch('lintly.parsers.ESLintParser._get_working_dir', return_value='/Users/grant/project')
-    def test_parse_violations(self, _get_working_dir_mock):
+    def test_parse_violations(self):
+        Config.BASE_DIR = '/Users/grant/project'
         super(ESLintParserTestCase, self).test_parse_violations()
 
 
@@ -168,8 +165,8 @@ class BlackParserTestCase(ParserTestCaseMixin, unittest.TestCase):
         for file_path in ['lintly/violations.py', 'lintly/parsers.py']
     }
 
-    @patch('lintly.parsers.BlackParser._get_working_dir', return_value='/Users/jouyuy/Dev/workspace/Lintly')
-    def test_parse_violations(self, _get_working_dir_mock):
+    def test_parse_violations(self):
+        Config.BASE_DIR = '/Users/jouyuy/Dev/workspace/Lintly'
         super(BlackParserTestCase, self).test_parse_violations()