--- a/Cargo.toml
+++ b/Cargo.toml
@@ -36,7 +36,3 @@
 [features]
-default = ["py"]
-py = [
-    "pyo3",
-    "pyo3/extension-module",
-]
+default = []
 trace = ["peg/trace"]
@@ -80,4 +80,4 @@
 [dependencies.pyo3]
-version = "0.25.1"
-optional = true
+version = ">= 0.25.1, < 1"
+features = ["extension-module"]
 
