diff --git a/Cargo.lock b/Cargo.lock
index b2a7afb..aeb0581 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -291,9 +291,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3"
-version = "0.20.3"
+version = "0.21.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "53bdbb96d49157e65d45cc287af5f32ffadd5f4761438b527b055fb0d4bb8233"
+checksum = "a02a88a17e74cadbc8ce77855e1d6c8ad0ab82901a4a9b5046bd01c1c0bd95cd"
 dependencies = [
  "cfg-if",
  "indoc",
@@ -309,9 +309,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3-build-config"
-version = "0.20.3"
+version = "0.21.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "deaa5745de3f5231ce10517a1f5dd97d53e5a2fd77aa6b5842292085831d48d7"
+checksum = "a5eb0b6ecba38961f6f4bd6cd5906dfab3cd426ff37b2eed5771006aa31656f1"
 dependencies = [
  "once_cell",
  "target-lexicon",
@@ -319,9 +319,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3-ffi"
-version = "0.20.3"
+version = "0.21.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "62b42531d03e08d4ef1f6e85a2ed422eb678b8cd62b762e53891c05faf0d4afa"
+checksum = "ba8a6e48a29b5d22e4fdaf132d8ba8d3203ee9f06362d48f244346902a594ec3"
 dependencies = [
  "libc",
  "pyo3-build-config",
@@ -329,9 +329,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3-macros"
-version = "0.20.3"
+version = "0.21.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7305c720fa01b8055ec95e484a6eca7a83c841267f0dd5280f0c8b8551d2c158"
+checksum = "4e80493c5965f94a747d0782a607b2328a4eea5391327b152b00e2f3b001cede"
 dependencies = [
  "proc-macro2",
  "pyo3-macros-backend",
@@ -341,9 +341,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3-macros-backend"
-version = "0.20.3"
+version = "0.21.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7c7e9b68bb9c3149c5b0cade5d07f953d6d125eb4337723c4ccdb665f1f96185"
+checksum = "fcd7d86f42004025200e12a6a8119bd878329e6fddef8178eaafa4e4b5906c5b"
 dependencies = [
  "heck",
  "proc-macro2",
diff --git a/Cargo.toml b/Cargo.toml
index 664cfc3..fa92a66 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,4 +15,4 @@ crate-type = ["cdylib"]
 
 [dependencies]
 ammonia = "4.0.0"
-pyo3 = { version = "0.20.2", features = ["abi3-py37", "extension-module"] }
+pyo3 = { version = "0.21.0", features = ["abi3-py37", "gil-refs"] }
diff --git a/pyproject.toml b/pyproject.toml
index 07dd28c..19e5d9e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,3 +1,6 @@
 [build-system]
 requires = ["maturin>=1.0,<2.0"]
 build-backend = "maturin"
+
+[tool.maturin]
+features = ["pyo3/extension-module"]
diff --git a/src/lib.rs b/src/lib.rs
index 4571945..b408fd6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -125,14 +125,14 @@ fn clean(
             if let Some(callback) = attribute_filter {
                 cleaner.attribute_filter(move |element, attribute, value| {
                     Python::with_gil(|py| {
-                        let res = callback.call(
+                        let res = callback.call_bound(
                             py,
-                            PyTuple::new(
+                            PyTuple::new_bound(
                                 py,
                                 [
-                                    PyString::new(py, element),
-                                    PyString::new(py, attribute),
-                                    PyString::new(py, value),
+                                    PyString::new_bound(py, element),
+                                    PyString::new_bound(py, attribute),
+                                    PyString::new_bound(py, value),
                                 ],
                             ),
                             None,
@@ -154,14 +154,14 @@ fn clean(
                             }
                             Err(err) => err,
                         };
-                        err.write_unraisable(
+                        err.write_unraisable_bound(
                             py,
-                            Some(PyTuple::new(
+                            Some(&PyTuple::new_bound(
                                 py,
                                 [
-                                    PyString::new(py, element),
-                                    PyString::new(py, attribute),
-                                    PyString::new(py, value),
+                                    PyString::new_bound(py, element),
+                                    PyString::new_bound(py, attribute),
+                                    PyString::new_bound(py, value),
                                 ],
                             )),
                         );
@@ -231,7 +231,7 @@ fn is_html(py: Python, html: &str) -> bool {
 
 /// Python bindings to the ammonia HTML sanitization library ( https://github.com/rust-ammonia/ammonia ).
 #[pymodule]
-fn nh3(_py: Python, m: &PyModule) -> PyResult<()> {
+fn nh3(_py: Python, m: &Bound<PyModule>) -> PyResult<()> {
     m.add("__version__", env!("CARGO_PKG_VERSION"))?;
     m.add_function(wrap_pyfunction!(clean, m)?)?;
     m.add_function(wrap_pyfunction!(clean_text, m)?)?;