diff --git a/pyproject.toml b/pyproject.toml
index 9447c94..57884aa 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,7 +11,7 @@ license = {text = "Apache-2.0"}
 
 dependencies = [
     "pyarrow >= 8",
-    "polars >= 0.20.10",
+    "polars >= 0.20.10, <1.0",
     "jsonschema >= 4.0.0",
     "meds == 0.1.3",
     "typing_extensions >= 4.0",