diff --git a/pyo3-ffi/src/cpython/unicodeobject.rs b/pyo3-ffi/src/cpython/unicodeobject.rs
index 27b55ef8..7cd3bfbc 100644
--- a/pyo3-ffi/src/cpython/unicodeobject.rs
+++ b/pyo3-ffi/src/cpython/unicodeobject.rs
@@ -1,6 +1,7 @@
 #[cfg(not(PyPy))]
 use crate::Py_hash_t;
 use crate::{PyObject, Py_UCS1, Py_UCS2, Py_UCS4, Py_UNICODE, Py_ssize_t};
+#[cfg(not(Py_3_12))]
 use libc::wchar_t;
 use std::os::raw::{c_char, c_int, c_uint, c_void};
 
@@ -116,6 +117,28 @@ where
     }
 }
 
+const STATE_INTERNED_INDEX: usize = 0;
+#[cfg(not(Py_3_12))]
+const STATE_INTERNED_WIDTH: u8 = 2;
+#[cfg(Py_3_12)]
+const STATE_INTERNED_WIDTH: u8 = 1;
+
+const STATE_KIND_INDEX: usize = STATE_INTERNED_WIDTH as usize;
+const STATE_KIND_WIDTH: u8 = 3;
+
+const STATE_COMPACT_INDEX: usize = (STATE_INTERNED_WIDTH + STATE_KIND_WIDTH) as usize;
+const STATE_COMPACT_WIDTH: u8 = 1;
+
+const STATE_ASCII_INDEX: usize =
+    (STATE_INTERNED_WIDTH + STATE_KIND_WIDTH + STATE_COMPACT_WIDTH) as usize;
+const STATE_ASCII_WIDTH: u8 = 1;
+
+#[cfg(not(Py_3_12))]
+const STATE_READY_INDEX: usize =
+    (STATE_INTERNED_WIDTH + STATE_KIND_WIDTH + STATE_COMPACT_WIDTH + STATE_ASCII_WIDTH) as usize;
+#[cfg(not(Py_3_12))]
+const STATE_READY_WIDTH: u8 = 1;
+
 // generated by bindgen v0.63.0 (with small adaptations)
 // The same code is generated for Python 3.7, 3.8, 3.9, 3.10, and 3.11, but the "ready" field
 // has been removed from Python 3.12.
@@ -137,57 +160,67 @@ struct PyASCIIObjectState {
 impl PyASCIIObjectState {
     #[inline]
     unsafe fn interned(&self) -> c_uint {
-        std::mem::transmute(self._bitfield.get(0usize, 2u8) as u32)
+        std::mem::transmute(
+            self._bitfield
+                .get(STATE_INTERNED_INDEX, STATE_INTERNED_WIDTH) as u32,
+        )
     }
 
     #[inline]
     unsafe fn set_interned(&mut self, val: c_uint) {
         let val: u32 = std::mem::transmute(val);
-        self._bitfield.set(0usize, 2u8, val as u64)
+        self._bitfield
+            .set(STATE_INTERNED_INDEX, STATE_INTERNED_WIDTH, val as u64)
     }
 
     #[inline]
     unsafe fn kind(&self) -> c_uint {
-        std::mem::transmute(self._bitfield.get(2usize, 3u8) as u32)
+        std::mem::transmute(self._bitfield.get(STATE_KIND_INDEX, STATE_KIND_WIDTH) as u32)
     }
 
     #[inline]
     unsafe fn set_kind(&mut self, val: c_uint) {
         let val: u32 = std::mem::transmute(val);
-        self._bitfield.set(2usize, 3u8, val as u64)
+        self._bitfield
+            .set(STATE_KIND_INDEX, STATE_KIND_WIDTH, val as u64)
     }
 
     #[inline]
     unsafe fn compact(&self) -> c_uint {
-        std::mem::transmute(self._bitfield.get(5usize, 1u8) as u32)
+        std::mem::transmute(self._bitfield.get(STATE_COMPACT_INDEX, STATE_COMPACT_WIDTH) as u32)
     }
 
     #[inline]
     unsafe fn set_compact(&mut self, val: c_uint) {
         let val: u32 = std::mem::transmute(val);
-        self._bitfield.set(5usize, 1u8, val as u64)
+        self._bitfield
+            .set(STATE_COMPACT_INDEX, STATE_COMPACT_WIDTH, val as u64)
     }
 
     #[inline]
     unsafe fn ascii(&self) -> c_uint {
-        std::mem::transmute(self._bitfield.get(6usize, 1u8) as u32)
+        std::mem::transmute(self._bitfield.get(STATE_ASCII_INDEX, STATE_ASCII_WIDTH) as u32)
     }
 
     #[inline]
     unsafe fn set_ascii(&mut self, val: c_uint) {
         let val: u32 = std::mem::transmute(val);
-        self._bitfield.set(6usize, 1u8, val as u64)
+        self._bitfield
+            .set(STATE_ASCII_INDEX, STATE_ASCII_WIDTH, val as u64)
     }
 
+    #[cfg(not(Py_3_12))]
     #[inline]
     unsafe fn ready(&self) -> c_uint {
-        std::mem::transmute(self._bitfield.get(7usize, 1u8) as u32)
+        std::mem::transmute(self._bitfield.get(STATE_READY_INDEX, STATE_READY_WIDTH) as u32)
     }
 
+    #[cfg(not(Py_3_12))]
     #[inline]
     unsafe fn set_ready(&mut self, val: c_uint) {
         let val: u32 = std::mem::transmute(val);
-        self._bitfield.set(7usize, 1u8, val as u64)
+        self._bitfield
+            .set(STATE_READY_INDEX, STATE_READY_WIDTH, val as u64)
     }
 }
 
@@ -226,6 +259,7 @@ pub struct PyASCIIObject {
     /// unsigned int ready:1;
     /// unsigned int :24;
     pub state: u32,
+    #[cfg(not(Py_3_12))]
     pub wstr: *mut wchar_t,
 }
 
@@ -233,7 +267,8 @@ pub struct PyASCIIObject {
 impl PyASCIIObject {
     /// Get the `interned` field of the [`PyASCIIObject`] state bitfield.
     ///
-    /// Returns one of: [`SSTATE_NOT_INTERNED`], [`SSTATE_INTERNED_MORTAL`], [`SSTATE_INTERNED_IMMORTAL`]
+    /// Returns one of: [`SSTATE_NOT_INTERNED`], [`SSTATE_INTERNED_MORTAL`],
+    /// or on CPython earlier than 3.12, [`SSTATE_INTERNED_IMMORTAL`]
     #[inline]
     pub unsafe fn interned(&self) -> c_uint {
         PyASCIIObjectState::from(self.state).interned()
@@ -242,7 +277,8 @@ impl PyASCIIObject {
     /// Set the `interned` field of the [`PyASCIIObject`] state bitfield.
     ///
     /// Calling this function with an argument that is not [`SSTATE_NOT_INTERNED`],
-    /// [`SSTATE_INTERNED_MORTAL`], or [`SSTATE_INTERNED_IMMORTAL`] is invalid.
+    /// [`SSTATE_INTERNED_MORTAL`], or on CPython earlier than 3.12,
+    /// [`SSTATE_INTERNED_IMMORTAL`] is invalid.
     #[inline]
     pub unsafe fn set_interned(&mut self, val: c_uint) {
         let mut state = PyASCIIObjectState::from(self.state);
@@ -309,6 +345,7 @@ impl PyASCIIObject {
     /// Get the `ready` field of the [`PyASCIIObject`] state bitfield.
     ///
     /// Returns either `0` or `1`.
+    #[cfg(not(Py_3_12))]
     #[inline]
     pub unsafe fn ready(&self) -> c_uint {
         PyASCIIObjectState::from(self.state).ready()
@@ -317,6 +354,7 @@ impl PyASCIIObject {
     /// Set the `ready` flag of the [`PyASCIIObject`] state bitfield.
     ///
     /// Calling this function with an argument that is neither `0` nor `1` is invalid.
+    #[cfg(not(Py_3_12))]
     #[inline]
     pub unsafe fn set_ready(&mut self, val: c_uint) {
         let mut state = PyASCIIObjectState::from(self.state);
@@ -330,6 +368,7 @@ pub struct PyCompactUnicodeObject {
     pub _base: PyASCIIObject,
     pub utf8_length: Py_ssize_t,
     pub utf8: *mut c_char,
+    #[cfg(not(Py_3_12))]
     pub wstr_length: Py_ssize_t,
 }
 
@@ -359,6 +398,7 @@ extern "C" {
 
 pub const SSTATE_NOT_INTERNED: c_uint = 0;
 pub const SSTATE_INTERNED_MORTAL: c_uint = 1;
+#[cfg(not(Py_3_12))]
 pub const SSTATE_INTERNED_IMMORTAL: c_uint = 2;
 
 #[inline]
@@ -449,6 +489,14 @@ pub unsafe fn PyUnicode_GET_LENGTH(op: *mut PyObject) -> Py_ssize_t {
     (*(op as *mut PyASCIIObject)).length
 }
 
+#[cfg(Py_3_12)]
+#[inline]
+pub unsafe fn PyUnicode_IS_READY(_op: *mut PyObject) -> c_uint {
+    // kept in CPython for backwards compatibility
+    1
+}
+
+#[cfg(not(Py_3_12))]
 #[inline]
 pub unsafe fn PyUnicode_IS_READY(op: *mut PyObject) -> c_uint {
     (*(op as *mut PyASCIIObject)).ready()
diff --git a/pyo3-ffi/src/unicodeobject.rs b/pyo3-ffi/src/unicodeobject.rs
index 5841fa9e..86075475 100644
--- a/pyo3-ffi/src/unicodeobject.rs
+++ b/pyo3-ffi/src/unicodeobject.rs
@@ -83,6 +83,8 @@ extern "C" {
     pub fn PyUnicode_FromFormat(format: *const c_char, ...) -> *mut PyObject;
     #[cfg_attr(PyPy, link_name = "PyPyUnicode_InternInPlace")]
     pub fn PyUnicode_InternInPlace(arg1: *mut *mut PyObject);
+    #[cfg(not(Py_3_12))]
+    #[cfg_attr(Py_3_10, deprecated(note = "Python 3.10"))]
     pub fn PyUnicode_InternImmortal(arg1: *mut *mut PyObject);
     #[cfg_attr(PyPy, link_name = "PyPyUnicode_InternFromString")]
     pub fn PyUnicode_InternFromString(u: *const c_char) -> *mut PyObject;