diff --git a/build.rs b/build.rs
index 7f1060acc14..cffdccf2add 100644
--- a/build.rs
+++ b/build.rs
@@ -486,7 +486,7 @@ print(json.dumps({
     serde_json::from_str(&json).map_err(|e| format!("Deserializing failed: {}", e))
 }
 
-fn configure(interpreter_config: &InterpreterConfig) -> Result<(String), String> {
+fn configure(interpreter_config: &InterpreterConfig) -> Result<String, String> {
     if let Some(minor) = interpreter_config.version.minor {
         if minor < PY3_MIN_MINOR {
             return Err(format!(
diff --git a/pyo3-derive-backend/src/method.rs b/pyo3-derive-backend/src/method.rs
index 31e68b02fa5..b195978044b 100644
--- a/pyo3-derive-backend/src/method.rs
+++ b/pyo3-derive-backend/src/method.rs
@@ -24,7 +24,6 @@ pub enum FnType {
     Setter(Option<String>),
     Fn,
     FnNew,
-    FnInit,
     FnCall,
     FnClass,
     FnStatic,
@@ -291,7 +290,10 @@ fn parse_attributes(attrs: &mut Vec<syn::Attribute>) -> syn::Result<(FnType, Vec
                 if name.is_ident("new") || name.is_ident("__new__") {
                     res = Some(FnType::FnNew)
                 } else if name.is_ident("init") || name.is_ident("__init__") {
-                    res = Some(FnType::FnInit)
+                    return Err(syn::Error::new_spanned(
+                        name,
+                        "#[init] is disabled from PyO3 0.9.0",
+                    ));
                 } else if name.is_ident("call") || name.is_ident("__call__") {
                     res = Some(FnType::FnCall)
                 } else if name.is_ident("classmethod") {
@@ -322,7 +324,10 @@ fn parse_attributes(attrs: &mut Vec<syn::Attribute>) -> syn::Result<(FnType, Vec
                 if path.is_ident("new") {
                     res = Some(FnType::FnNew)
                 } else if path.is_ident("init") {
-                    res = Some(FnType::FnInit)
+                    return Err(syn::Error::new_spanned(
+                        path,
+                        "#[init] is disabled from PyO3 0.9.0",
+                    ));
                 } else if path.is_ident("call") {
                     res = Some(FnType::FnCall)
                 } else if path.is_ident("setter") || path.is_ident("getter") {
diff --git a/pyo3-derive-backend/src/pymethod.rs b/pyo3-derive-backend/src/pymethod.rs
index 2f561cb9d8d..9a0d3eff814 100644
--- a/pyo3-derive-backend/src/pymethod.rs
+++ b/pyo3-derive-backend/src/pymethod.rs
@@ -24,7 +24,6 @@ pub fn gen_py_method(
             &impl_wrap_pyslf(cls, name, &spec, self_ty, true),
         ),
         FnType::FnNew => impl_py_method_def_new(name, doc, &impl_wrap_new(cls, name, &spec)),
-        FnType::FnInit => impl_py_method_def_init(name, doc, &impl_wrap_init(cls, name, &spec)),
         FnType::FnCall => impl_py_method_def_call(name, doc, &impl_wrap(cls, name, &spec, false)),
         FnType::FnClass => impl_py_method_def_class(name, doc, &impl_wrap_class(cls, name, &spec)),
         FnType::FnStatic => {
@@ -220,45 +219,6 @@ pub fn impl_wrap_new(cls: &syn::Type, name: &syn::Ident, spec: &FnSpec<'_>) -> T
     }
 }
 
-/// Generate function wrapper for ffi::initproc
-fn impl_wrap_init(cls: &syn::Type, name: &syn::Ident, spec: &FnSpec<'_>) -> TokenStream {
-    let cb = impl_call(cls, name, &spec);
-    let output = &spec.output;
-    let result_empty: syn::Type = syn::parse_quote!(PyResult<()>);
-    let empty: syn::Type = syn::parse_quote!(());
-    if output != &result_empty || output != &empty {
-        panic!("Constructor must return PyResult<()> or a ()");
-    }
-
-    let body = impl_arg_params(&spec, cb);
-
-    quote! {
-        #[allow(unused_mut)]
-        unsafe extern "C" fn __wrap(
-            _slf: *mut pyo3::ffi::PyObject,
-            _args: *mut pyo3::ffi::PyObject,
-            _kwargs: *mut pyo3::ffi::PyObject) -> pyo3::libc::c_int
-        {
-            const _LOCATION: &'static str = concat!(stringify!(#cls),".",stringify!(#name),"()");
-            let _py = pyo3::Python::assume_gil_acquired();
-            let _pool = pyo3::GILPool::new(_py);
-            let _slf = _py.mut_from_borrowed_ptr::<#cls>(_slf);
-            let _args = _py.from_borrowed_ptr::<pyo3::types::PyTuple>(_args);
-            let _kwargs: Option<&pyo3::types::PyDict> = _py.from_borrowed_ptr_or_opt(_kwargs);
-
-            #body
-
-            match _result {
-                Ok(_) => 0,
-                Err(e) => {
-                    e.restore(_py);
-                    -1
-                }
-            }
-        }
-    }
-}
-
 /// Generate class method wrapper (PyCFunction, PyCFunctionWithKeywords)
 pub fn impl_wrap_class(cls: &syn::Type, name: &syn::Ident, spec: &FnSpec<'_>) -> TokenStream {
     let names: Vec<syn::Ident> = get_arg_names(&spec);
@@ -612,25 +572,6 @@ pub fn impl_py_method_def_new(
     }
 }
 
-pub fn impl_py_method_def_init(
-    name: &syn::Ident,
-    doc: syn::Lit,
-    wrapper: &TokenStream,
-) -> TokenStream {
-    quote! {
-        pyo3::class::PyMethodDefType::Init({
-            #wrapper
-
-            pyo3::class::PyMethodDef {
-                ml_name: stringify!(#name),
-                ml_meth: pyo3::class::PyMethodType::PyInitFunc(__wrap),
-                ml_flags: pyo3::ffi::METH_VARARGS | pyo3::ffi::METH_KEYWORDS,
-                ml_doc: #doc,
-            }
-        })
-    }
-}
-
 pub fn impl_py_method_def_class(
     name: &syn::Ident,
     doc: syn::Lit,
diff --git a/src/class/methods.rs b/src/class/methods.rs
index 362f78bcfd5..f52a50ce6e9 100644
--- a/src/class/methods.rs
+++ b/src/class/methods.rs
@@ -10,8 +10,6 @@ use std::ffi::CString;
 pub enum PyMethodDefType {
     /// Represents class `__new__` method
     New(PyMethodDef),
-    /// Represents class `__init__` method
-    Init(PyMethodDef),
     /// Represents class `__call__` method
     Call(PyMethodDef),
     /// Represents class method
diff --git a/src/type_object.rs b/src/type_object.rs
index 4cdd2d8dba6..1c1a493e94f 100644
--- a/src/type_object.rs
+++ b/src/type_object.rs
@@ -372,23 +372,14 @@ where
     type_object.tp_as_buffer = to_ptr(<T as class::buffer::PyBufferProtocolImpl>::tp_as_buffer());
 
     // normal methods
-    let (new, init, call, mut methods) = py_class_method_defs::<T>();
+    let (new, call, mut methods) = py_class_method_defs::<T>();
     if !methods.is_empty() {
         methods.push(ffi::PyMethodDef_INIT);
         type_object.tp_methods = Box::into_raw(methods.into_boxed_slice()) as *mut _;
     }
 
-    if let (None, Some(_)) = (new, init) {
-        panic!(
-            "{}.__new__ method is required if __init__ method defined",
-            T::NAME
-        );
-    }
-
     // __new__ method
     type_object.tp_new = new;
-    // __init__ method
-    type_object.tp_init = init;
     // __call__ method
     type_object.tp_call = call;
 
@@ -440,14 +431,12 @@ fn py_class_flags<T: PyTypeInfo>(type_object: &mut ffi::PyTypeObject) {
 
 fn py_class_method_defs<T: PyMethodsProtocol>() -> (
     Option<ffi::newfunc>,
-    Option<ffi::initproc>,
     Option<ffi::PyCFunctionWithKeywords>,
     Vec<ffi::PyMethodDef>,
 ) {
     let mut defs = Vec::new();
     let mut call = None;
     let mut new = None;
-    let mut init = None;
 
     for def in T::py_methods() {
         match *def {
@@ -463,13 +452,6 @@ fn py_class_method_defs<T: PyMethodsProtocol>() -> (
                     panic!("Method type is not supoorted by tp_call slot")
                 }
             }
-            PyMethodDefType::Init(ref def) => {
-                if let class::methods::PyMethodType::PyInitFunc(meth) = def.ml_meth {
-                    init = Some(meth)
-                } else {
-                    panic!("Method type is not supoorted by tp_init slot")
-                }
-            }
             PyMethodDefType::Method(ref def)
             | PyMethodDefType::Class(ref def)
             | PyMethodDefType::Static(ref def) => {
@@ -497,7 +479,7 @@ fn py_class_method_defs<T: PyMethodsProtocol>() -> (
 
     py_class_async_methods::<T>(&mut defs);
 
-    (new, init, call, defs)
+    (new, call, defs)
 }
 
 fn py_class_async_methods<T>(defs: &mut Vec<ffi::PyMethodDef>) {