diff --git a/optional_requirements.txt b/optional_requirements.txt
index 60e3fb4bac5cf62f9d4c92dcc277686efe4ac0d3..07934750c2813dda21a70b5982f855a3496cb91e 100644
--- a/optional_requirements.txt
+++ b/optional_requirements.txt
@@ -1,3 +1,4 @@
 celerite
 george
 plotly
+pytest-requires