diff --git a/setup.py b/setup.py
index 834163e..5dfe2da 100644
--- a/setup.py
+++ b/setup.py
@@ -51,6 +51,7 @@
             "pytest >= 3.6",
             "coverage",
             "pytest-cov",
+            "time-machine>=2.14.1, <3.0.0",
         ],
     },
     test_suite="tests",