diff --git a/requirements.txt b/requirements.txt
index 95f6c6f..c5a660b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,5 @@
 absl-py==1.0.0
 dm-tree==0.1.6
-numpy==1.22.0
+numpy==1.21.6; python_version < '3.8'
+numpy==1.22.0; python_version >= '3.8'
 pytest==6.2.5