diff --git a/src/lib.rs b/src/lib.rs
index 1366b81..413e176 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -115,10 +115,10 @@
 //!     // Generic associated types, the return values are moved to here.
 //!     // NOTE: all #[send] methods also get the `Send` trait bound.
 //!     type OpenFuture<'a>: ::core::future::Future<Output = Result<FileDescriptor, Errno>> +
-//!         ::core::marker::Send + 'a;
-//!     type ReadFuture<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a;
-//!     type WriteFuture<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a;
-//!     type CloseFuture<'a>: ::core::future::Future<Output = Result<(), Errno>> + 'a;
+//!         ::core::marker::Send + 'a where Self: 'a;
+//!     type ReadFuture<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a where Self: 'a;
+//!     type WriteFuture<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a where Self: 'a;
+//!     type CloseFuture<'a>: ::core::future::Future<Output = Result<(), Errno>> + 'a where Self: 'a;
 //! }
 //! ```
 //!
@@ -133,10 +133,10 @@
 //! #   fn read<'a>(&'a self, fd: FileDescriptor, buf: &'a mut [u8]) -> Self::ReadFuture<'a>;
 //! #   fn write<'a>(&'a self, fd: FileDescriptor, buf: &'a [u8]) -> Self::WriteFuture<'a>;
 //! #   fn close<'a>(&'a self, fd: FileDescriptor) -> Self::CloseFuture<'a>;
-//! #   type OpenFuture<'a>: ::core::future::Future<Output = Result<FileDescriptor, Errno>> + Send + 'a;
-//! #   type ReadFuture<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a;
-//! #   type WriteFuture<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a;
-//! #   type CloseFuture<'a>: ::core::future::Future<Output = Result<(), Errno>> + 'a;
+//! #   type OpenFuture<'a>: ::core::future::Future<Output = Result<FileDescriptor, Errno>> + Send + 'a where Self: 'a;
+//! #   type ReadFuture<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a where Self: 'a;
+//! #   type WriteFuture<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a where Self: 'a;
+//! #   type CloseFuture<'a>: ::core::future::Future<Output = Result<(), Errno>> + 'a where Self: 'a;
 //! # }
 //! # const ENOENT: Errno = Errno;
 //! # const EBADF: Errno = Errno;
@@ -188,13 +188,15 @@
 
 extern crate proc_macro;
 
+use std::iter::FromIterator;
 use std::str::FromStr;
 use std::{iter, mem};
 
 use proc_macro2::{Span, TokenStream};
 use quote::quote;
 use syn::punctuated::Punctuated;
-use syn::token;
+use syn::token::Where;
+use syn::{token, PredicateType, WhereClause, WherePredicate};
 use syn::{
     AngleBracketedGenericArguments, AttrStyle, Attribute, Binding, Block, Expr, ExprAsync, FnArg,
     GenericArgument, GenericParam, Generics, Ident, ImplItem, ImplItemType, ItemImpl, ItemTrait,
@@ -311,7 +313,32 @@ fn handle_item_impl(mut item: ItemImpl) -> TokenStream {
             generics: Generics {
                 lt_token: Some(Token!(<)(Span::call_site())),
                 gt_token: Some(Token!(>)(Span::call_site())),
-                where_clause: None,
+                where_clause: Some(WhereClause {
+                    where_token: Where::default(),
+                    predicates: function_lifetimes
+                        .iter()
+                        .cloned()
+                        .map(|lifetimedef| {
+                            WherePredicate::Type(PredicateType {
+                                colon_token: Token!(:)(Span::call_site()),
+                                lifetimes: None,
+                                bounded_ty: Type::Path(TypePath {
+                                    qself: None,
+                                    path: Path {
+                                        leading_colon: None,
+                                        segments: Punctuated::from_iter([PathSegment {
+                                            ident: Ident::new("Self", Span::call_site()),
+                                            arguments: PathArguments::None,
+                                        }]),
+                                    },
+                                }),
+                                bounds: Punctuated::from_iter([TypeParamBound::Lifetime(
+                                    lifetimedef.lifetime,
+                                )]),
+                            })
+                        })
+                        .collect(),
+                }),
                 params: function_lifetimes
                     .iter()
                     .cloned()
@@ -590,7 +617,32 @@ fn handle_item_trait(mut item: ItemTrait) -> TokenStream {
             generics: Generics {
                 lt_token: Some(Token!(<)(Span::call_site())),
                 gt_token: Some(Token!(>)(Span::call_site())),
-                where_clause: None,
+                where_clause: Some(WhereClause {
+                    where_token: Where::default(),
+                    predicates: function_lifetimes
+                        .iter()
+                        .cloned()
+                        .map(|lifetimedef| {
+                            WherePredicate::Type(PredicateType {
+                                colon_token: Token!(:)(Span::call_site()),
+                                lifetimes: None,
+                                bounded_ty: Type::Path(TypePath {
+                                    qself: None,
+                                    path: Path {
+                                        leading_colon: None,
+                                        segments: Punctuated::from_iter([PathSegment {
+                                            ident: Ident::new("Self", Span::call_site()),
+                                            arguments: PathArguments::None,
+                                        }]),
+                                    },
+                                }),
+                                bounds: Punctuated::from_iter([TypeParamBound::Lifetime(
+                                    lifetimedef.lifetime,
+                                )]),
+                            })
+                        })
+                        .collect(),
+                }),
                 params: function_lifetimes
                     .iter()
                     .cloned()
diff --git a/src/tests.rs b/src/tests.rs
index 228529a..2b1b684 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -16,10 +16,10 @@ fn correct_trait_output() {
             fn write<'a>(&'a mut self, fd: usize, buf: &'a [u8]) -> Self::__real_async_trait_impl_TypeFor_write<'a>;
             fn close<'a>(&'a mut self, fd: usize) -> Self::__real_async_trait_impl_TypeFor_close<'a>;
 
-            type __real_async_trait_impl_TypeFor_open<'a>: ::core::future::Future<Output = Result<usize, Errno>> + ::core::marker::Send + 'a;
-            type __real_async_trait_impl_TypeFor_read<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a;
-            type __real_async_trait_impl_TypeFor_write<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a;
-            type __real_async_trait_impl_TypeFor_close<'a>: ::core::future::Future<Output = Result<(), Errno>> + 'a;
+            type __real_async_trait_impl_TypeFor_open<'a>: ::core::future::Future<Output = Result<usize, Errno>> + ::core::marker::Send + 'a where Self: 'a;
+            type __real_async_trait_impl_TypeFor_read<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a where Self: 'a;
+            type __real_async_trait_impl_TypeFor_write<'a>: ::core::future::Future<Output = Result<usize, Errno>> + 'a where Self: 'a;
+            type __real_async_trait_impl_TypeFor_close<'a>: ::core::future::Future<Output = Result<(), Errno>> + 'a where Self: 'a;
         }
     };
     let actual_output = crate::real_async_trait2(proc_macro2::TokenStream::new(), input);
@@ -65,10 +65,10 @@ fn correct_impl_output() {
                     async move { Ok(()) }
                 }
 
-                type __real_async_trait_impl_TypeFor_open<'a> = __real_async_trait_impl_ExistentialTypeFor_open<'a>;
-                type __real_async_trait_impl_TypeFor_read<'a> = __real_async_trait_impl_ExistentialTypeFor_read<'a>;
-                type __real_async_trait_impl_TypeFor_write<'a> = __real_async_trait_impl_ExistentialTypeFor_write<'a>;
-                type __real_async_trait_impl_TypeFor_close<'a> = __real_async_trait_impl_ExistentialTypeFor_close<'a>;
+                type __real_async_trait_impl_TypeFor_open<'a> = __real_async_trait_impl_ExistentialTypeFor_open<'a> where Self: 'a;
+                type __real_async_trait_impl_TypeFor_read<'a> = __real_async_trait_impl_ExistentialTypeFor_read<'a> where Self: 'a;
+                type __real_async_trait_impl_TypeFor_write<'a> = __real_async_trait_impl_ExistentialTypeFor_write<'a> where Self: 'a;
+                type __real_async_trait_impl_TypeFor_close<'a> = __real_async_trait_impl_ExistentialTypeFor_close<'a> where Self: 'a;
             }
             type __real_async_trait_impl_ExistentialTypeFor_open<'a> = impl ::core::future::Future<Output = Result<usize, Errno>> + ::core::marker::Send + 'a;
             type __real_async_trait_impl_ExistentialTypeFor_read<'a> = impl ::core::future::Future<Output = Result<usize, Errno>> + 'a;