diff --git a/setup.cfg b/setup.cfg
index f645003..8aa3835 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -48,7 +48,7 @@ install_requires =
   importlib-metadata >=4.0      ; python_version < '3.10'
   importlib-resources >=1.0     ; python_version < '3.9'
   numpy ~=1.16
-  polars ~=0.20.0
+  polars >=0.16,<0.21
   psutil ~=5.8
   pyhmmer ~=0.10.0
   pyrodigal ~=3.0