--- a/tests/test_ansi2html.py
+++ b/tests/test_ansi2html.py
@@ -27,7 +27,7 @@ from io import StringIO
 from os.path import abspath, dirname, join
 from subprocess import run
 
-from mock import patch
+from unittest.mock import patch
 
 from ansi2html import Ansi2HTMLConverter
 from ansi2html.converter import (
--- a/tox.ini
+++ b/tox.ini
@@ -10,8 +10,6 @@ setenv =
     PYTHONWARNINGS=error::FutureWarning
     # Aim to replace with below once other issues are fixed:
     # PYTHONWARNINGS=error
-deps =
-    mock
 sitepackages = False
 commands =
     python -m unittest tests/test_ansi2html.py