diff --git a/.travis.yml b/.travis.yml
index dbd3a3f5..08074800 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,7 +10,7 @@ install:
   - python -c "import sysconfig; print('\n'.join(map(repr,sorted(sysconfig.get_config_vars().items()))))"
   - mkdir ~/rust-installer
   - curl -sL https://static.rust-lang.org/rustup.sh -o ~/rust-installer/rustup.sh
-  - sh ~/rust-installer/rustup.sh --prefix=~/rust --spec=$RUST_VERSION -y --disable-sudo
+  - sh ~/rust-installer/rustup.sh --prefix=~/rust --spec=$RUST_VERSION -y
   - export PATH="$HOME/rust/bin:$PATH"
   - export PYTHON_LIB=$(python -c "import sysconfig; print(sysconfig.get_config_var('LIBDIR'))")
   - find $PYTHON_LIB
diff --git a/pyo3cls/src/func.rs b/pyo3cls/src/func.rs
index e3626eca..94476cb8 100644
--- a/pyo3cls/src/func.rs
+++ b/pyo3cls/src/func.rs
@@ -9,6 +9,10 @@ pub enum MethodProto {
     Unary{name: &'static str, proto: &'static str},
     Binary{name: &'static str, arg: &'static str, proto: &'static str},
     Ternary{name: &'static str, arg1: &'static str, arg2: &'static str, proto: &'static str},
+    Quaternary{name: &'static str,
+               arg1: &'static str,
+               arg2: &'static str,
+               arg3: &'static str, proto: &'static str},
 }
 
 impl MethodProto {
@@ -19,6 +23,7 @@ impl MethodProto {
             MethodProto::Unary{name: n, proto: _} => n == name,
             MethodProto::Binary{name: n, arg: _, proto: _} => n == name,
             MethodProto::Ternary{name: n, arg1: _, arg2: _, proto: _} => n == name,
+            MethodProto::Quaternary{name: n, arg1: _, arg2: _, arg3: _, proto: _} => n == name,
         }
     }
 }
@@ -80,6 +85,26 @@ pub fn impl_method_proto(cls: &Box<syn::Ty>,
                         }
                     }
                 },
+                MethodProto::Quaternary{name: _, arg1, arg2, arg3, proto} => {
+                    let p = syn::Ident::from(proto);
+                    let arg1_name = syn::Ident::from(arg1);
+                    let arg1_ty = get_arg_ty(sig, 2);
+                    let arg2_name = syn::Ident::from(arg2);
+                    let arg2_ty = get_arg_ty(sig, 3);
+                    let arg3_name = syn::Ident::from(arg3);
+                    let arg3_ty = get_arg_ty(sig, 4);
+                    let succ = get_res_success(ty);
+
+                    quote! {
+                        impl #p for #cls {
+                            type #arg1_name = #arg1_ty;
+                            type #arg2_name = #arg2_ty;
+                            type #arg3_name = #arg3_ty;
+                            type Success = #succ;
+                            type Result = #ty;
+                        }
+                    }
+                },
             }
         },
         _ => panic!("not supported"),
@@ -87,10 +112,31 @@ pub fn impl_method_proto(cls: &Box<syn::Ty>,
 }
 
 
+// TODO: better arg ty detection
 fn get_arg_ty(sig: &syn::MethodSig, idx: usize) -> syn::Ty {
     match sig.decl.inputs[idx] {
         syn::FnArg::Captured(_, ref arg_ty) => {
-            arg_ty.clone()
+            match arg_ty {
+                &syn::Ty::Path(_, ref path) => {
+                    // use only last path segment for Option<>
+                    let seg = path.segments.last().unwrap().clone();
+                    if seg.ident.as_ref() == "Option" {
+                        match seg.parameters {
+                            syn::PathParameters::AngleBracketed(ref data) => {
+                                if let Some(ty) = data.types.last() {
+                                    return ty.clone()
+                                }
+                            }
+                            _ => (),
+                        }
+                    }
+
+                    arg_ty.clone()
+                },
+                _ => {
+                    arg_ty.clone()
+                }
+            }
         },
         _ =>
             panic!("not supported"),
diff --git a/pyo3cls/src/py_impl.rs b/pyo3cls/src/py_impl.rs
index ecaa5a94..d593549f 100644
--- a/pyo3cls/src/py_impl.rs
+++ b/pyo3cls/src/py_impl.rs
@@ -25,9 +25,9 @@ fn impl_methods(ty: &Box<syn::Ty>, impls: &mut Vec<syn::ImplItem>) -> Tokens {
     let mut methods = Vec::new();
     for iimpl in impls.iter_mut() {
         match iimpl.node {
-            syn::ImplItemKind::Method(ref mut sig, ref mut block) => {
+            syn::ImplItemKind::Method(ref mut sig, _) => {
                 methods.push(py_method::gen_py_method(
-                    ty, &iimpl.ident, sig, block, &mut iimpl.attrs));
+                    ty, &iimpl.ident, sig, &mut iimpl.attrs));
             },
             _ => (),
         }
diff --git a/pyo3cls/src/py_method.rs b/pyo3cls/src/py_method.rs
index f01e5870..be2425cb 100644
--- a/pyo3cls/src/py_method.rs
+++ b/pyo3cls/src/py_method.rs
@@ -29,7 +29,7 @@ enum FnSpec {
 
 
 pub fn gen_py_method<'a>(cls: &Box<syn::Ty>, name: &syn::Ident,
-                         sig: &mut syn::MethodSig, _block: &mut syn::Block,
+                         sig: &mut syn::MethodSig,
                          meth_attrs: &mut Vec<syn::Attribute>) -> Tokens
 {
     check_generic(name, sig);
diff --git a/pyo3cls/src/py_proto.rs b/pyo3cls/src/py_proto.rs
index 18030e7b..2e87a557 100644
--- a/pyo3cls/src/py_proto.rs
+++ b/pyo3cls/src/py_proto.rs
@@ -11,10 +11,15 @@ struct Methods {
     methods: &'static [&'static str],
 }
 
+struct PyMethod {
+    name: &'static str,
+    proto: &'static str,
+}
+
 struct Proto {
     name: &'static str,
-    //py_methods: &'static [&'static str],
     methods: &'static [MethodProto],
+    py_methods: &'static [PyMethod],
 }
 
 static DEFAULT_METHODS: Methods = Methods {
@@ -40,9 +45,8 @@ static NUM_METHODS: Methods = Methods {
 
 static ASYNC: Proto = Proto {
     name: "Async",
-    //py_methods: &[],
     methods: &[
-        MethodProto::Unary{
+        MethodProto::Unary {
             name: "__await__",
             proto: "_pyo3::class::async::PyAsyncAwaitProtocol"},
         MethodProto::Unary{
@@ -51,12 +55,29 @@ static ASYNC: Proto = Proto {
         MethodProto::Unary{
             name: "__anext__",
             proto: "_pyo3::class::async::PyAsyncAnextProtocol"},
+        MethodProto::Unary{
+            name: "__aenter__",
+            proto: "_pyo3::class::async::PyAsyncAenterProtocol"},
+        MethodProto::Quaternary {
+            name: "__aexit__",
+            arg1: "ExcType", arg2: "ExcValue", arg3: "Traceback",
+            proto: "_pyo3::class::async::PyAsyncAexitProtocol"},
+    ],
+    py_methods: &[
+        PyMethod {
+            name: "__aenter__",
+            proto: "_pyo3::class::async::PyAsyncAenterProtocolImpl",
+        },
+        PyMethod {
+            name: "__aexit__",
+            proto: "_pyo3::class::async::PyAsyncAexitProtocolImpl",
+        },
     ],
 };
 
 static ITER: Proto = Proto {
     name: "Iter",
-    //py_methods: &[],
+    py_methods: &[],
     methods: &[
         MethodProto::Unary{
             name: "__iter__",
@@ -70,7 +91,7 @@ static ITER: Proto = Proto {
 
 static MAPPING: Proto = Proto {
     name: "Mapping",
-    //py_methods: &[],
+    py_methods: &[],
     methods: &[
         MethodProto::Len{
             name: "__len__",
@@ -140,6 +161,7 @@ pub fn build_py_proto(ast: &mut syn::Item) -> Tokens {
 
 fn impl_proto_impl(ty: &Box<syn::Ty>, impls: &mut Vec<syn::ImplItem>, proto: &Proto) -> Tokens {
     let mut tokens = Tokens::new();
+    let mut py_methods = Vec::new();
 
     for iimpl in impls.iter_mut() {
         match iimpl.node {
@@ -149,6 +171,27 @@ fn impl_proto_impl(ty: &Box<syn::Ty>, impls: &mut Vec<syn::ImplItem>, proto: &Pr
                         impl_method_proto(ty, sig, m).to_tokens(&mut tokens);
                     }
                 }
+                for m in proto.py_methods {
+                    if m.name == iimpl.ident.as_ref() {
+                        let name = syn::Ident::from(m.name);
+                        let proto = syn::Ident::from(m.proto);
+
+                        let meth = py_method::gen_py_method(
+                            ty, &iimpl.ident, sig, &mut iimpl.attrs);
+
+                        py_methods.push(
+                            quote! {
+                                impl #proto for #ty
+                                {
+                                    #[inline]
+                                    fn #name() -> Option<_pyo3::class::methods::PyMethodDefType> {
+                                        Some(#meth)
+                                    }
+                                }
+                            }
+                        );
+                    }
+                }
             },
             _ => (),
         }
@@ -172,6 +215,8 @@ fn impl_proto_impl(ty: &Box<syn::Ty>, impls: &mut Vec<syn::ImplItem>, proto: &Pr
             extern crate pyo3 as _pyo3;
 
             #tokens
+
+            #(#py_methods)*
         };
     }
 }
@@ -185,10 +230,10 @@ fn impl_protocol(name: &'static str,
     let mut meth = Vec::new();
     for iimpl in impls.iter_mut() {
         match iimpl.node {
-            syn::ImplItemKind::Method(ref mut sig, ref mut block) => {
+            syn::ImplItemKind::Method(ref mut sig, _) => {
                 if methods.methods.contains(&iimpl.ident.as_ref()) {
                     py_methods.push(py_method::gen_py_method(
-                        ty, &iimpl.ident, sig, block, &mut iimpl.attrs));
+                        ty, &iimpl.ident, sig, &mut iimpl.attrs));
                 } else {
                     meth.push(String::from(iimpl.ident.as_ref()));
                 }
diff --git a/src/class/async.rs b/src/class/async.rs
index e68ad5c8..7e1ab8f7 100644
--- a/src/class/async.rs
+++ b/src/class/async.rs
@@ -10,6 +10,7 @@ use ffi;
 use err::PyResult;
 use python::{Python, PythonObject};
 use callback::PyObjectCallbackConverter;
+use class::methods::{PyMethodDef, PyMethodDefType};
 
 
 /// Awaitable interface
@@ -28,9 +29,11 @@ pub trait PyAsyncProtocol: PythonObject {
     fn __aenter__(&self, py: Python)
                   -> Self::Result where Self: PyAsyncAenterProtocol { unimplemented!() }
 
-    fn __aexit__(&self, py: Python)
+    fn __aexit__(&self, py: Python,
+                 exc_type: Option<Self::ExcType>,
+                 exc_value: Option<Self::ExcValue>,
+                 traceback: Option<Self::Traceback>)
                  -> Self::Result where Self: PyAsyncAexitProtocol { unimplemented!() }
-
 }
 
 
@@ -55,6 +58,9 @@ pub trait PyAsyncAenterProtocol: PyAsyncProtocol {
 }
 
 pub trait PyAsyncAexitProtocol: PyAsyncProtocol {
+    type ExcType: for<'a> ::FromPyObject<'a>;
+    type ExcValue: for<'a> ::FromPyObject<'a>;
+    type Traceback: for<'a> ::FromPyObject<'a>;
     type Success: ::ToPyObject;
     type Result: Into<PyResult<Self::Success>>;
 }
@@ -63,6 +69,8 @@ pub trait PyAsyncAexitProtocol: PyAsyncProtocol {
 #[doc(hidden)]
 pub trait PyAsyncProtocolImpl {
     fn tp_as_async() -> Option<ffi::PyAsyncMethods>;
+
+    fn methods() -> Vec<PyMethodDef>;
 }
 
 impl<T> PyAsyncProtocolImpl for T {
@@ -70,6 +78,11 @@ impl<T> PyAsyncProtocolImpl for T {
     default fn tp_as_async() -> Option<ffi::PyAsyncMethods> {
         None
     }
+
+    #[inline]
+    default fn methods() -> Vec<PyMethodDef> {
+        Vec::new()
+    }
 }
 
 impl<T> PyAsyncProtocolImpl for T where T: PyAsyncProtocol {
@@ -81,6 +94,22 @@ impl<T> PyAsyncProtocolImpl for T where T: PyAsyncProtocol {
             am_anext: Self::am_anext(),
         })
     }
+
+    #[inline]
+    fn methods() -> Vec<PyMethodDef> {
+        let mut methods = Vec::new();
+
+        if let Some(PyMethodDefType::Method(meth)) =
+            <Self as PyAsyncAenterProtocolImpl>::__aenter__() {
+                methods.push(meth)
+            }
+        if let Some(PyMethodDefType::Method(meth)) =
+            <Self as PyAsyncAexitProtocolImpl>::__aexit__() {
+                methods.push(meth)
+        }
+
+        methods
+    }
 }
 
 
@@ -151,45 +180,27 @@ impl<T> PyAsyncAnextProtocolImpl for T
 }
 
 trait PyAsyncAenterProtocolImpl {
-    fn am_aenter() -> Option<ffi::unaryfunc>;
+    fn __aenter__() -> Option<PyMethodDefType>;
 }
 
 impl<T> PyAsyncAenterProtocolImpl for T
     where T: PyAsyncProtocol
 {
     #[inline]
-    default fn am_aenter() -> Option<ffi::unaryfunc> {
+    default fn __aenter__() -> Option<PyMethodDefType> {
         None
     }
 }
 
-impl<T> PyAsyncAenterProtocolImpl for T
-    where T: PyAsyncAenterProtocol
-{
-    #[inline]
-    fn am_aenter() -> Option<ffi::unaryfunc> {
-        py_unary_func_!(PyAsyncAenterProtocol, T::__aenter__, PyObjectCallbackConverter)
-    }
-}
-
-trait PyAsyncAexitProtocolImpl {
-    fn am_aexit() -> Option<ffi::unaryfunc>;
+pub trait PyAsyncAexitProtocolImpl {
+    fn __aexit__() -> Option<PyMethodDefType>;
 }
 
 impl<T> PyAsyncAexitProtocolImpl for T
     where T: PyAsyncProtocol
 {
     #[inline]
-    default fn am_aexit() -> Option<ffi::unaryfunc> {
+    default fn __aexit__() -> Option<PyMethodDefType> {
         None
     }
 }
-
-impl<T> PyAsyncAexitProtocolImpl for T
-    where T: PyAsyncAexitProtocol
-{
-    #[inline]
-    fn am_aexit() -> Option<ffi::unaryfunc> {
-        py_unary_func_!(PyAsyncAexitProtocol, T::__aexit__, PyObjectCallbackConverter)
-    }
-}
diff --git a/src/class/methods.rs b/src/class/methods.rs
index bc9ea355..cc508421 100644
--- a/src/class/methods.rs
+++ b/src/class/methods.rs
@@ -15,6 +15,7 @@ pub enum PyMethodDefType {
 pub enum PyMethodType {
     PyCFunction(ffi::PyCFunction),
     PyCFunctionWithKeywords(ffi::PyCFunctionWithKeywords),
+    PyNoArgsFunction(ffi::PyNoArgsFunction),
 }
 
 #[derive(Copy, Clone)]
@@ -56,7 +57,12 @@ impl PyMethodDef {
                 unsafe {
                     ::std::mem::transmute::<
                             ffi::PyCFunctionWithKeywords, ffi::PyCFunction>(meth)
-                }
+                },
+            PyMethodType::PyNoArgsFunction(meth) =>
+                unsafe {
+                    ::std::mem::transmute::<
+                            ffi::PyNoArgsFunction, ffi::PyCFunction>(meth)
+                },
         };
 
         ffi::PyMethodDef {
diff --git a/src/class/typeob.rs b/src/class/typeob.rs
index 46446e5e..e0e9a25c 100644
--- a/src/class/typeob.rs
+++ b/src/class/typeob.rs
@@ -193,6 +193,9 @@ fn py_class_method_defs<T>() -> Vec<ffi::PyMethodDef> {
             _ => (),
         }
     }
+    for def in <T as class::async::PyAsyncProtocolImpl>::methods() {
+        defs.push(def.as_method_def())
+    }
 
     defs
 }