diff --git a/dev-requirements.txt b/dev-requirements.txt
index 8a48753..dda1833 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -1,5 +1,5 @@
 autopep8==1.4.4
-mock==3.0.5
+mock==4.0.0
 pylint==2.3.1; python_version >= "3.4"
 pylint==1.9.4; python_version >= "2" and python_version < "3.4"
 pytest==5.0.0; python_version >= "3.4"