diff --git a/requirements-dev.txt b/requirements-dev.txt
index 9a249c9..94c623e 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -4,7 +4,7 @@ numpy==1.15.2
 future==0.16.0
 pytest==3.8.1
 pytest-pep8==1.0.6
-mock==2.0.0
+mock==4.0.2
 scikit-learn==0.20.0
 pytest-cov==2.6.0
 coveralls==1.5.0
\ No newline at end of file