diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
index 020ca37..e1a1090 100644
--- a/.cargo_vcs_info.json
+++ b/.cargo_vcs_info.json
@@ -1,5 +1,5 @@
 {
   "git": {
-    "sha1": "29f01e8f33414f20a953dd1363277ac5d1cf7974"
+    "sha1": "35b1fa620a6486ed4b544d4fec6aa8cbdd017bd6"
   }
 }
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..fea412f
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,22 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+  schedule: [cron: "40 1 * * *"]
+
+jobs:
+  test:
+    name: Rust ${{matrix.rust}}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        rust: [nightly, beta, stable, 1.31.0]
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{matrix.rust}}
+      - run: cargo run --manifest-path example/Cargo.toml
+      - run: cargo test --all
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 3e6107d..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,13 +0,0 @@
-sudo: false
-
-language: rust
-
-rust:
-  - nightly
-  - beta
-  - stable
-  - 1.31.0
-
-script:
-  - cargo run --manifest-path example/Cargo.toml
-  - cargo test --all
diff --git a/Cargo.toml b/Cargo.toml
index 66f7685..102757c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,7 +13,7 @@
 [package]
 edition = "2018"
 name = "proc-macro-hack"
-version = "0.5.15"
+version = "0.5.16"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 description = "Procedural macros in expression position"
 readme = "README.md"
@@ -42,5 +42,3 @@
 
 [dev-dependencies.trybuild]
 version = "1.0"
-[badges.travis-ci]
-repository = "dtolnay/proc-macro-hack"
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
index 3076694..1f75add 100644
--- a/Cargo.toml.orig
+++ b/Cargo.toml.orig
@@ -1,6 +1,6 @@
 [package]
 name = "proc-macro-hack"
-version = "0.5.15"
+version = "0.5.16"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
@@ -20,9 +20,6 @@
 syn = "1.0.5"
 trybuild = "1.0"
 
-[badges]
-travis-ci = { repository = "dtolnay/proc-macro-hack" }
-
 [workspace]
 members = ["demo-hack", "demo-hack-impl", "example", "nested"]
 
diff --git a/METADATA b/METADATA
index 1b6ac6b..932bd30 100644
--- a/METADATA
+++ b/METADATA
@@ -9,11 +9,11 @@
     type: GIT
     value: "https://github.com/dtolnay/proc-macro-hack"
   }
-  version: "0.5.15"
+  version: "0.5.16"
   license_type: NOTICE
   last_upgrade_date {
     year: 2020
-    month: 4
-    day: 17
+    month: 5
+    day: 25
   }
 }
diff --git a/README.md b/README.md
index 7984e6d..d6a6463 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,10 @@
 Procedural macros in expression position
 ========================================
 
-[![Build Status](https://api.travis-ci.org/dtolnay/proc-macro-hack.svg?branch=master)](https://travis-ci.org/dtolnay/proc-macro-hack)
-[![Latest Version](https://img.shields.io/crates/v/proc-macro-hack.svg)](https://crates.io/crates/proc-macro-hack)
+[<img alt="github" src="https://img.shields.io/badge/github-dtolnay/proc--macro--hack-8da0cb?style=for-the-badge&labelColor=555555&logo=github" height="20">](https://github.com/dtolnay/proc-macro-hack)
+[<img alt="crates.io" src="https://img.shields.io/crates/v/proc-macro-hack.svg?style=for-the-badge&color=fc8d62&logo=rust" height="20">](https://crates.io/crates/proc-macro-hack)
+[<img alt="docs.rs" src="https://img.shields.io/badge/docs.rs-proc--macro--hack-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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" height="20">](https://docs.rs/proc-macro-hack)
+[<img alt="build status" src="https://img.shields.io/github/workflow/status/dtolnay/proc-macro-hack/CI/master?style=for-the-badge" height="20">](https://github.com/dtolnay/proc-macro-hack/actions?query=branch%3Amaster)
 
 As of Rust 1.30, the language supports user-defined function-like procedural
 macros. However these can only be invoked in item position, not in
@@ -22,7 +24,7 @@
 This crate must contain nothing but procedural macros. Private helper
 functions and private modules are fine but nothing can be public.
 
-[> example of an implementation crate][demo-hack-impl]
+[&raquo; example of an implementation crate][demo-hack-impl]
 
 Just like you would use a #\[proc_macro\] attribute to define a natively
 supported procedural macro, use proc-macro-hack's #\[proc_macro_hack\]
@@ -52,7 +54,7 @@
 This crate is allowed to contain other public things if you need, for
 example traits or functions or ordinary macros.
 
-[> example of a declaration crate][demo-hack]
+[&raquo; example of a declaration crate][demo-hack]
 
 Within the declaration crate there needs to be a re-export of your
 procedural macro from the implementation crate. The re-export also carries a
@@ -88,7 +90,7 @@
 Users of your crate depend on your declaration crate (not your
 implementation crate), then use your procedural macros as usual.
 
-[> example of a downstream crate][example]
+[&raquo; example of a downstream crate][example]
 
 ```rust
 use demo_hack::add_one;
diff --git a/src/iter.rs b/src/iter.rs
new file mode 100644
index 0000000..722013c
--- /dev/null
+++ b/src/iter.rs
@@ -0,0 +1,42 @@
+use proc_macro::{token_stream, Delimiter, TokenStream, TokenTree};
+
+pub type Iter<'a> = &'a mut IterImpl;
+
+pub struct IterImpl {
+    stack: Vec<token_stream::IntoIter>,
+    peeked: Option<TokenTree>,
+}
+
+pub fn new(tokens: TokenStream) -> IterImpl {
+    IterImpl {
+        stack: vec![tokens.into_iter()],
+        peeked: None,
+    }
+}
+
+impl IterImpl {
+    pub fn peek(&mut self) -> Option<&TokenTree> {
+        self.peeked = self.next();
+        self.peeked.as_ref()
+    }
+}
+
+impl Iterator for IterImpl {
+    type Item = TokenTree;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if let Some(tt) = self.peeked.take() {
+            return Some(tt);
+        }
+        loop {
+            let top = self.stack.last_mut()?;
+            match top.next() {
+                None => drop(self.stack.pop()),
+                Some(TokenTree::Group(ref group)) if group.delimiter() == Delimiter::None => {
+                    self.stack.push(group.stream().into_iter());
+                }
+                Some(tt) => return Some(tt),
+            }
+        }
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 292ac74..16d7823 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,11 @@
+//! [![github]](https://github.com/dtolnay/proc-macro-hack)&ensp;[![crates-io]](https://crates.io/crates/proc-macro-hack)&ensp;[![docs-rs]](https://docs.rs/proc-macro-hack)
+//!
+//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
+//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
+//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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
+//!
+//! <br>
+//!
 //! As of Rust 1.30, the language supports user-defined function-like procedural
 //! macros. However these can only be invoked in item position, not in
 //! statements or expressions.
@@ -14,7 +22,7 @@
 //! This crate must contain nothing but procedural macros. Private helper
 //! functions and private modules are fine but nothing can be public.
 //!
-//! [> example of an implementation crate][demo-hack-impl]
+//! [&raquo; example of an implementation crate][demo-hack-impl]
 //!
 //! Just like you would use a #\[proc_macro\] attribute to define a natively
 //! supported procedural macro, use proc-macro-hack's #\[proc_macro_hack\]
@@ -48,7 +56,7 @@
 //! This crate is allowed to contain other public things if you need, for
 //! example traits or functions or ordinary macros.
 //!
-//! [> example of a declaration crate][demo-hack]
+//! [&raquo; example of a declaration crate][demo-hack]
 //!
 //! Within the declaration crate there needs to be a re-export of your
 //! procedural macro from the implementation crate. The re-export also carries a
@@ -86,7 +94,7 @@
 //! Users of your crate depend on your declaration crate (not your
 //! implementation crate), then use your procedural macros as usual.
 //!
-//! [> example of a downstream crate][example]
+//! [&raquo; example of a downstream crate][example]
 //!
 //! ```
 //! use demo_hack::add_one;
@@ -131,15 +139,17 @@
 mod quote;
 
 mod error;
+mod iter;
 mod parse;
 
 use crate::error::{compile_error, Error};
-use crate::parse::*;
-use proc_macro::{token_stream, Ident, Punct, Spacing, Span, TokenStream, TokenTree};
+use crate::iter::Iter;
+use crate::parse::{
+    parse_define_args, parse_enum_hack, parse_export_args, parse_fake_call_site, parse_input,
+};
+use proc_macro::{Ident, Punct, Spacing, Span, TokenStream, TokenTree};
 use std::fmt::Write;
-use std::iter::Peekable;
 
-type Iter<'a> = &'a mut Peekable<token_stream::IntoIter>;
 type Visibility = Option<Span>;
 
 enum Input {
@@ -169,8 +179,8 @@
 
 #[proc_macro_attribute]
 pub fn proc_macro_hack(args: TokenStream, input: TokenStream) -> TokenStream {
-    let ref mut args = args.into_iter().peekable();
-    let ref mut input = input.into_iter().peekable();
+    let ref mut args = iter::new(args);
+    let ref mut input = iter::new(input);
     expand_proc_macro_hack(args, input).unwrap_or_else(compile_error)
 }
 
@@ -190,7 +200,7 @@
 #[doc(hidden)]
 #[proc_macro_derive(ProcMacroHack)]
 pub fn enum_hack(input: TokenStream) -> TokenStream {
-    let ref mut input = input.into_iter().peekable();
+    let ref mut input = iter::new(input);
     parse_enum_hack(input).unwrap_or_else(compile_error)
 }
 
@@ -202,8 +212,8 @@
 #[doc(hidden)]
 #[proc_macro_attribute]
 pub fn fake_call_site(args: TokenStream, input: TokenStream) -> TokenStream {
-    let ref mut args = args.into_iter().peekable();
-    let ref mut input = input.into_iter().peekable();
+    let ref mut args = iter::new(args);
+    let ref mut input = iter::new(input);
     expand_fake_call_site(args, input).unwrap_or_else(compile_error)
 }
 
diff --git a/src/parse.rs b/src/parse.rs
index c6b1665..de7c599 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -1,7 +1,7 @@
-use crate::{Define, Error, Export, ExportArgs, FakeCallSite, Input, Iter, Macro, Visibility};
+use crate::iter::{self, Iter, IterImpl};
+use crate::{Define, Error, Export, ExportArgs, FakeCallSite, Input, Macro, Visibility};
 use proc_macro::Delimiter::{Brace, Bracket, Parenthesis};
-use proc_macro::{token_stream, Delimiter, Ident, Span, TokenStream, TokenTree};
-use std::iter::Peekable;
+use proc_macro::{Delimiter, Ident, Span, TokenStream, TokenTree};
 
 pub(crate) fn parse_input(tokens: Iter) -> Result<Input, Error> {
     let attrs = parse_attributes(tokens)?;
@@ -29,7 +29,7 @@
     let mut macros = Vec::new();
     match tokens.peek() {
         Some(TokenTree::Group(group)) if group.delimiter() == Brace => {
-            let ref mut content = group.stream().into_iter().peekable();
+            let ref mut content = iter::new(group.stream());
             loop {
                 macros.push(parse_macro(content)?);
                 if content.peek().is_none() {
@@ -124,13 +124,10 @@
     }
 }
 
-fn parse_group(
-    tokens: Iter,
-    delimiter: Delimiter,
-) -> Result<Peekable<token_stream::IntoIter>, Error> {
+fn parse_group(tokens: Iter, delimiter: Delimiter) -> Result<IterImpl, Error> {
     match &tokens.next() {
         Some(TokenTree::Group(group)) if group.delimiter() == delimiter => {
-            Ok(group.stream().into_iter().peekable())
+            Ok(iter::new(group.stream()))
         }
         tt => Err(Error::new(
             tt.as_ref().map_or_else(Span::call_site, TokenTree::span),