diff --git a/tests/requirements.txt b/tests/requirements.txt
index 9d691c036..b0248f010 100644
--- a/tests/requirements.txt
+++ b/tests/requirements.txt
@@ -2,3 +2,4 @@
 numpy; platform_python_implementation!="PyPy" or sys_platform!="darwin" or python_version<"3.0"
 numpy<1.19; platform_python_implementation=="PyPy" and sys_platform=="darwin" and python_version>="3.0"
 pytest
+scipy; (platform_python_implementation!="PyPy" or sys_platform!="darwin") and python_version<"3.9"