diff --git a/requirements.txt b/requirements.txt
index 82ee8ff..aaf89f1 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 numpy==1.16.3
 six==1.12.0
 sorcery==0.1.0
-pytest
+pytest==4.5.0
 cloudpickle