diff --git a/requirements.txt b/requirements.txt
index 62764725c..53313ba9e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -14,3 +14,4 @@ regex==2017.4.5
 ftfy>=4.4.2,<5.0.0
 pytest>=3.0.6,<4.0.0
 pip>=9.0.0,<10.0.0
+mock>=2.0.0,<3.0.0