diff --git a/tools/run-mypy b/tools/run-mypy
index 5cbbcb4077..d23f8300ae 100755
--- a/tools/run-mypy
+++ b/tools/run-mypy
@@ -24,29 +24,31 @@ zproject/test_settings.py
 """.split()
 
 parser = argparse.ArgumentParser(description="Run mypy on files tracked by git.")
-parser.add_argument('targets', nargs='*', default=[],
+parser.add_argument('targets', nargs='*',
                     help="""files and directories to include in the result.
                     If this is not specified, the current directory is used""")
-parser.add_argument('-m', '--modified', action='store_true', default=False, help='list only modified files')
-parser.add_argument('-a', '--all', dest='all', action='store_true', default=False,
+parser.add_argument('-m', '--modified', action='store_true',
+                    help='list only modified files')
+parser.add_argument('-a', '--all', action='store_true',
                     help="""run mypy on all python files, ignoring the exclude list.
                     This is useful if you have to find out which files fail mypy check.""")
-parser.add_argument('--linecoverage-report', dest='linecoverage_report', action='store_true', default=False,
+parser.add_argument('--linecoverage-report', action='store_true',
                     help="""run the linecoverage report to see annotation coverage""")
-parser.add_argument('--no-disallow-untyped-defs', dest='disallow_untyped_defs', action='store_false', default=True,
+parser.add_argument('--no-disallow-untyped-defs',
+                    dest='disallow_untyped_defs', action='store_false',
                     help="""Don't throw errors when functions are not annotated""")
-parser.add_argument('--scripts-only', dest='scripts_only', action='store_true', default=False,
+parser.add_argument('--scripts-only', action='store_true',
                     help="""Only type check extensionless python scripts""")
-parser.add_argument('--strict-optional', dest='strict_optional', action='store_true', default=False,
+parser.add_argument('--strict-optional', action='store_true',
                     help="""Use the --strict-optional flag with mypy""")
-parser.add_argument('--warn-unused-ignores', dest='warn_unused_ignores', action='store_true', default=False,
+parser.add_argument('--warn-unused-ignores', action='store_true',
                     help="""Use the --warn-unused-ignores flag with mypy""")
-parser.add_argument('--no-ignore-missing-imports', dest='ignore_missing_imports', action='store_false', default=True,
+parser.add_argument('--no-ignore-missing-imports',
+                    dest='ignore_missing_imports', action='store_false',
                     help="""Don't use the --ignore-missing-imports flag with mypy""")
-parser.add_argument('--quick', action='store_true', default=False,
+parser.add_argument('--quick', action='store_true',
                     help="""Use the --quick flag with mypy""")
-parser.add_argument('--force', default=False,
-                    action="store_true",
+parser.add_argument('--force', action="store_true",
                     help='Run tests despite possible provisioning problems.')
 args = parser.parse_args()