diff --git a/requirements.txt b/requirements.txt
index bf31d78e..61639968 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,6 +3,6 @@ matplotlib>=3.0
 numpy>=1.14
 numpydoc
 nbsphinx
-pytest
+pytest>=4.6
 pytest-cov
 scipy>=1.0