diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
index 8216174..020ca37 100644
--- a/.cargo_vcs_info.json
+++ b/.cargo_vcs_info.json
@@ -1,5 +1,5 @@
 {
   "git": {
-    "sha1": "d29a20e44207f915f42e6d1668d2864b0152e5a8"
+    "sha1": "29f01e8f33414f20a953dd1363277ac5d1cf7974"
   }
 }
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..3e6107d
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,13 @@
+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 0096538..66f7685 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,28 +13,34 @@
 [package]
 edition = "2018"
 name = "proc-macro-hack"
-version = "0.5.12"
+version = "0.5.15"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 description = "Procedural macros in expression position"
 readme = "README.md"
 categories = ["development-tools::procedural-macro-helpers"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/dtolnay/proc-macro-hack"
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
 
 [lib]
 proc-macro = true
-[dependencies.proc-macro2]
-version = "1.0"
-
-[dependencies.quote]
-version = "1.0"
-
-[dependencies.syn]
-version = "1.0.5"
 [dev-dependencies.demo-hack]
 version = "0.0.5"
 
 [dev-dependencies.demo-hack-impl]
 version = "0.0.5"
+
+[dev-dependencies.quote]
+version = "1.0"
+
+[dev-dependencies.rustversion]
+version = "1.0"
+
+[dev-dependencies.syn]
+version = "1.0.5"
+
+[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 ddc7286..3076694 100644
--- a/Cargo.toml.orig
+++ b/Cargo.toml.orig
@@ -1,6 +1,6 @@
 [package]
 name = "proc-macro-hack"
-version = "0.5.12"
+version = "0.5.15"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
@@ -12,17 +12,19 @@
 [lib]
 proc-macro = true
 
-[dependencies]
-proc-macro2 = "1.0"
-quote = "1.0"
-syn = "1.0.5"
-
 [dev-dependencies]
 demo-hack = { version = "0.0.5", path = "demo-hack" }
 demo-hack-impl = { version = "0.0.5", path = "demo-hack-impl" }
+quote = "1.0"
+rustversion = "1.0"
+syn = "1.0.5"
+trybuild = "1.0"
 
 [badges]
 travis-ci = { repository = "dtolnay/proc-macro-hack" }
 
 [workspace]
 members = ["demo-hack", "demo-hack-impl", "example", "nested"]
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
diff --git a/METADATA b/METADATA
index f5a6faa..1b6ac6b 100644
--- a/METADATA
+++ b/METADATA
@@ -1,7 +1,5 @@
 name: "proc-macro-hack"
-description:
-    "Procedural macros in expression position"
-
+description: "Procedural macros in expression position"
 third_party {
   url {
     type: HOMEPAGE
@@ -11,7 +9,11 @@
     type: GIT
     value: "https://github.com/dtolnay/proc-macro-hack"
   }
-  version: "0.5.12"
-  last_upgrade_date { year: 2020 month: 3 day: 19 }
+  version: "0.5.15"
   license_type: NOTICE
+  last_upgrade_date {
+    year: 2020
+    month: 4
+    day: 17
+  }
 }
diff --git a/OWNERS b/OWNERS
new file mode 100644
index 0000000..46fc303
--- /dev/null
+++ b/OWNERS
@@ -0,0 +1 @@
+include platform/prebuilts/rust:/OWNERS
diff --git a/src/error.rs b/src/error.rs
new file mode 100644
index 0000000..7334a53
--- /dev/null
+++ b/src/error.rs
@@ -0,0 +1,39 @@
+use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
+use std::iter::FromIterator;
+
+pub struct Error {
+    span: Span,
+    msg: String,
+}
+
+impl Error {
+    pub fn new(span: Span, msg: impl Into<String>) -> Self {
+        Error {
+            span,
+            msg: msg.into(),
+        }
+    }
+}
+
+pub fn compile_error(err: Error) -> TokenStream {
+    // compile_error!($msg)
+    TokenStream::from_iter(vec![
+        TokenTree::Ident(Ident::new("compile_error", err.span)),
+        TokenTree::Punct({
+            let mut punct = Punct::new('!', Spacing::Alone);
+            punct.set_span(err.span);
+            punct
+        }),
+        TokenTree::Group({
+            let mut group = Group::new(Delimiter::Brace, {
+                TokenStream::from_iter(vec![TokenTree::Literal({
+                    let mut string = Literal::string(&err.msg);
+                    string.set_span(err.span);
+                    string
+                })])
+            });
+            group.set_span(err.span);
+            group
+        }),
+    ])
+}
diff --git a/src/lib.rs b/src/lib.rs
index e9b80e6..292ac74 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -123,19 +123,24 @@
 //! [`proc-macro-nested`]: https://docs.rs/proc-macro-nested
 
 #![recursion_limit = "512"]
-#![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
-#![cfg_attr(feature = "cargo-clippy", allow(needless_pass_by_value))]
+#![allow(clippy::needless_doctest_main, clippy::toplevel_ref_arg)]
 
 extern crate proc_macro;
 
-use proc_macro2::{Span, TokenStream, TokenTree};
-use quote::{format_ident, quote, ToTokens};
-use std::fmt::Write;
-use syn::ext::IdentExt;
-use syn::parse::{Parse, ParseStream, Result};
-use syn::{braced, bracketed, parenthesized, parse_macro_input, token, Ident, LitInt, Token};
+#[macro_use]
+mod quote;
 
-type Visibility = Option<Token![pub]>;
+mod error;
+mod parse;
+
+use crate::error::{compile_error, Error};
+use crate::parse::*;
+use proc_macro::{token_stream, 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 {
     Export(Export),
@@ -162,122 +167,61 @@
     export_as: Ident,
 }
 
-impl Parse for Input {
-    fn parse(input: ParseStream) -> Result<Self> {
-        let ahead = input.fork();
-        parse_attributes(&ahead)?;
-        ahead.parse::<Visibility>()?;
-
-        if ahead.peek(Token![use]) {
-            input.parse().map(Input::Export)
-        } else if ahead.peek(Token![fn]) {
-            input.parse().map(Input::Define)
-        } else {
-            Err(input.error("unexpected input to #[proc_macro_hack]"))
-        }
-    }
-}
-
-impl Parse for Export {
-    fn parse(input: ParseStream) -> Result<Self> {
-        let attrs = input.call(parse_attributes)?;
-        let vis: Visibility = input.parse()?;
-        input.parse::<Token![use]>()?;
-        input.parse::<Option<Token![::]>>()?;
-        let from: Ident = input.parse()?;
-        input.parse::<Token![::]>()?;
-
-        let mut macros = Vec::new();
-        if input.peek(token::Brace) {
-            let content;
-            braced!(content in input);
-            loop {
-                macros.push(content.parse()?);
-                if content.is_empty() {
-                    break;
-                }
-                content.parse::<Token![,]>()?;
-                if content.is_empty() {
-                    break;
-                }
-            }
-        } else {
-            macros.push(input.parse()?);
-        }
-
-        input.parse::<Token![;]>()?;
-        Ok(Export {
-            attrs,
-            vis,
-            from,
-            macros,
-        })
-    }
-}
-
-impl Parse for Define {
-    fn parse(input: ParseStream) -> Result<Self> {
-        let attrs = input.call(parse_attributes)?;
-        let vis: Visibility = input.parse()?;
-        if vis.is_none() {
-            return Err(input.error("functions tagged with `#[proc_macro_hack]` must be `pub`"));
-        }
-
-        input.parse::<Token![fn]>()?;
-        let name: Ident = input.parse()?;
-        let body: TokenStream = input.parse()?;
-        Ok(Define { attrs, name, body })
-    }
-}
-
-impl Parse for Macro {
-    fn parse(input: ParseStream) -> Result<Self> {
-        let name: Ident = input.parse()?;
-        let renamed: Option<Token![as]> = input.parse()?;
-        let export_as = if renamed.is_some() {
-            input.parse()?
-        } else {
-            name.clone()
-        };
-        Ok(Macro { name, export_as })
-    }
-}
-
-fn parse_attributes(input: ParseStream) -> Result<TokenStream> {
-    let mut attrs = TokenStream::new();
-    while input.peek(Token![#]) {
-        let pound: Token![#] = input.parse()?;
-        pound.to_tokens(&mut attrs);
-        let content;
-        let bracket_token = bracketed!(content in input);
-        let content: TokenStream = content.parse()?;
-        bracket_token.surround(&mut attrs, |tokens| content.to_tokens(tokens));
-    }
-    Ok(attrs)
-}
-
 #[proc_macro_attribute]
-pub fn proc_macro_hack(
-    args: proc_macro::TokenStream,
-    input: proc_macro::TokenStream,
-) -> proc_macro::TokenStream {
-    proc_macro::TokenStream::from(match parse_macro_input!(input) {
+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();
+    expand_proc_macro_hack(args, input).unwrap_or_else(compile_error)
+}
+
+fn expand_proc_macro_hack(args: Iter, input: Iter) -> Result<TokenStream, Error> {
+    match parse_input(input)? {
         Input::Export(export) => {
-            let args = parse_macro_input!(args as ExportArgs);
-            expand_export(export, args)
+            let args = parse_export_args(args)?;
+            Ok(expand_export(export, args))
         }
         Input::Define(define) => {
-            parse_macro_input!(args as DefineArgs);
-            expand_define(define)
+            parse_define_args(args)?;
+            Ok(expand_define(define))
         }
-    })
+    }
 }
 
-mod kw {
-    syn::custom_keyword!(derive);
-    syn::custom_keyword!(fake_call_site);
-    syn::custom_keyword!(internal_macro_calls);
-    syn::custom_keyword!(support_nested);
+#[doc(hidden)]
+#[proc_macro_derive(ProcMacroHack)]
+pub fn enum_hack(input: TokenStream) -> TokenStream {
+    let ref mut input = input.into_iter().peekable();
+    parse_enum_hack(input).unwrap_or_else(compile_error)
+}
+
+struct FakeCallSite {
+    derive: Ident,
+    rest: TokenStream,
+}
+
+#[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();
+    expand_fake_call_site(args, input).unwrap_or_else(compile_error)
+}
+
+fn expand_fake_call_site(args: Iter, input: Iter) -> Result<TokenStream, Error> {
+    let span = match args.next() {
+        Some(token) => token.span(),
+        None => return Ok(input.collect()),
+    };
+
+    let input = parse_fake_call_site(input)?;
+    let mut derive = input.derive;
+    derive.set_span(span);
+    let rest = input.rest;
+
+    Ok(quote! {
+        #[derive(#derive)]
+        #rest
+    })
 }
 
 struct ExportArgs {
@@ -286,151 +230,25 @@
     fake_call_site: bool,
 }
 
-impl Parse for ExportArgs {
-    fn parse(input: ParseStream) -> Result<Self> {
-        let mut args = ExportArgs {
-            support_nested: false,
-            internal_macro_calls: 0,
-            fake_call_site: false,
-        };
-
-        while !input.is_empty() {
-            let ahead = input.lookahead1();
-            if ahead.peek(kw::support_nested) {
-                input.parse::<kw::support_nested>()?;
-                args.support_nested = true;
-            } else if ahead.peek(kw::internal_macro_calls) {
-                input.parse::<kw::internal_macro_calls>()?;
-                input.parse::<Token![=]>()?;
-                let calls = input.parse::<LitInt>()?.base10_parse()?;
-                args.internal_macro_calls = calls;
-            } else if ahead.peek(kw::fake_call_site) {
-                input.parse::<kw::fake_call_site>()?;
-                args.fake_call_site = true;
-            } else {
-                return Err(ahead.error());
-            }
-            if input.is_empty() {
-                break;
-            }
-            input.parse::<Token![,]>()?;
-        }
-
-        Ok(args)
-    }
-}
-
-struct DefineArgs;
-
-impl Parse for DefineArgs {
-    fn parse(_input: ParseStream) -> Result<Self> {
-        Ok(DefineArgs)
-    }
-}
-
-struct EnumHack {
-    token_stream: TokenStream,
-}
-
-impl Parse for EnumHack {
-    fn parse(input: ParseStream) -> Result<Self> {
-        input.parse::<Token![enum]>()?;
-        input.parse::<Ident>()?;
-
-        let braces;
-        braced!(braces in input);
-        braces.parse::<Ident>()?;
-        braces.parse::<Token![=]>()?;
-
-        let parens;
-        parenthesized!(parens in braces);
-        parens.parse::<Ident>()?;
-        parens.parse::<Token![!]>()?;
-
-        let inner;
-        braced!(inner in parens);
-        let token_stream: TokenStream = inner.parse()?;
-
-        parens.parse::<Token![,]>()?;
-        parens.parse::<TokenTree>()?;
-        braces.parse::<Token![.]>()?;
-        braces.parse::<TokenTree>()?;
-        braces.parse::<Token![,]>()?;
-
-        Ok(EnumHack { token_stream })
-    }
-}
-
-#[doc(hidden)]
-#[proc_macro_derive(ProcMacroHack)]
-pub fn enum_hack(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
-    let inner = parse_macro_input!(input as EnumHack);
-    proc_macro::TokenStream::from(inner.token_stream)
-}
-
-struct FakeCallSite {
-    derive: Ident,
-    rest: TokenStream,
-}
-
-impl Parse for FakeCallSite {
-    fn parse(input: ParseStream) -> Result<Self> {
-        input.parse::<Token![#]>()?;
-        let attr;
-        bracketed!(attr in input);
-        attr.parse::<kw::derive>()?;
-        let path;
-        parenthesized!(path in attr);
-        Ok(FakeCallSite {
-            derive: path.parse()?,
-            rest: input.parse()?,
-        })
-    }
-}
-
-#[doc(hidden)]
-#[proc_macro_attribute]
-pub fn fake_call_site(
-    args: proc_macro::TokenStream,
-    input: proc_macro::TokenStream,
-) -> proc_macro::TokenStream {
-    let args = TokenStream::from(args);
-    let span = match args.into_iter().next() {
-        Some(token) => token.span(),
-        None => return input,
-    };
-
-    let input = parse_macro_input!(input as FakeCallSite);
-    let mut derive = input.derive;
-    derive.set_span(span);
-    let rest = input.rest;
-
-    let expanded = quote! {
-        #[derive(#derive)]
-        #rest
-    };
-
-    proc_macro::TokenStream::from(expanded)
-}
-
 fn expand_export(export: Export, args: ExportArgs) -> TokenStream {
     let dummy = dummy_name_for_export(&export);
 
     let attrs = export.attrs;
-    let vis = export.vis;
+    let ref vis = export.vis.map(|span| Ident::new("pub", span));
     let macro_export = match vis {
         Some(_) => quote!(#[macro_export]),
         None => quote!(),
     };
-    let crate_prefix = vis.map(|_| quote!($crate::));
+    let crate_prefix = vis.as_ref().map(|_| quote!($crate::));
     let enum_variant = if args.support_nested {
         if args.internal_macro_calls == 0 {
-            quote!(Nested)
+            Ident::new("Nested", Span::call_site())
         } else {
-            format_ident!("Nested{}", args.internal_macro_calls).to_token_stream()
+            let name = format!("Nested{}", args.internal_macro_calls);
+            Ident::new(&name, Span::call_site())
         }
     } else {
-        quote!(Value)
+        Ident::new("Value", Span::call_site())
     };
 
     let from = export.from;
@@ -452,9 +270,11 @@
             };
 
             let proc_macro_call = if args.support_nested {
-                let extra_bangs = (0..args.internal_macro_calls).map(|_| quote!(!));
+                let extra_bangs = (0..args.internal_macro_calls)
+                    .map(|_| TokenTree::Punct(Punct::new('!', Spacing::Alone)))
+                    .collect::<TokenStream>();
                 quote! {
-                    #crate_prefix #dispatch! { ($($proc_macro)*) #(#extra_bangs)* }
+                    #crate_prefix #dispatch! { ($($proc_macro)*) #extra_bangs }
                 }
             } else {
                 quote! {
@@ -500,6 +320,7 @@
                 macro_rules! #export_as {
                     ($($proc_macro:tt)*) => {{
                         #do_derive
+                        #[allow(dead_code)]
                         enum ProcMacroHack {
                             #enum_variant = (stringify! { $($proc_macro)* }, 0).1,
                         }
@@ -533,6 +354,8 @@
             let mut iter = input.into_iter();
             iter.next().unwrap(); // `enum`
             iter.next().unwrap(); // `ProcMacroHack`
+            iter.next().unwrap(); // `#`
+            iter.next().unwrap(); // `[allow(dead_code)]`
 
             let mut braces = match iter.next().unwrap() {
                 #dummy::TokenTree::Group(group) => group.stream().into_iter(),
@@ -624,28 +447,46 @@
 }
 
 fn actual_proc_macro_name(conceptual: &Ident) -> Ident {
-    format_ident!("proc_macro_hack_{}", conceptual)
+    Ident::new(
+        &format!("proc_macro_hack_{}", conceptual),
+        conceptual.span(),
+    )
 }
 
 fn dispatch_macro_name(conceptual: &Ident) -> Ident {
-    format_ident!("proc_macro_call_{}", conceptual)
+    Ident::new(
+        &format!("proc_macro_call_{}", conceptual),
+        conceptual.span(),
+    )
 }
 
 fn call_site_macro_name(conceptual: &Ident) -> Ident {
-    format_ident!("proc_macro_fake_call_site_{}", conceptual)
+    Ident::new(
+        &format!("proc_macro_fake_call_site_{}", conceptual),
+        conceptual.span(),
+    )
 }
 
 fn dummy_name_for_export(export: &Export) -> String {
     let mut dummy = String::new();
-    let from = export.from.unraw().to_string();
+    let from = unraw(&export.from).to_string();
     write!(dummy, "_{}{}", from.len(), from).unwrap();
     for m in &export.macros {
-        let name = m.name.unraw().to_string();
+        let name = unraw(&m.name).to_string();
         write!(dummy, "_{}{}", name.len(), name).unwrap();
     }
     dummy
 }
 
+fn unraw(ident: &Ident) -> Ident {
+    let string = ident.to_string();
+    if string.starts_with("r#") {
+        Ident::new(&string[2..], ident.span())
+    } else {
+        ident.clone()
+    }
+}
+
 fn wrap_in_enum_hack(dummy: String, inner: TokenStream) -> TokenStream {
     let dummy = Ident::new(&dummy, Span::call_site());
     quote! {
diff --git a/src/parse.rs b/src/parse.rs
new file mode 100644
index 0000000..c6b1665
--- /dev/null
+++ b/src/parse.rs
@@ -0,0 +1,248 @@
+use crate::{Define, Error, Export, ExportArgs, FakeCallSite, Input, Iter, Macro, Visibility};
+use proc_macro::Delimiter::{Brace, Bracket, Parenthesis};
+use proc_macro::{token_stream, Delimiter, Ident, Span, TokenStream, TokenTree};
+use std::iter::Peekable;
+
+pub(crate) fn parse_input(tokens: Iter) -> Result<Input, Error> {
+    let attrs = parse_attributes(tokens)?;
+    let vis = parse_visibility(tokens)?;
+    let kw = parse_ident(tokens)?;
+    if kw.to_string() == "use" {
+        parse_export(attrs, vis, tokens).map(Input::Export)
+    } else if kw.to_string() == "fn" {
+        parse_define(attrs, vis, kw.span(), tokens).map(Input::Define)
+    } else {
+        Err(Error::new(
+            kw.span(),
+            "unexpected input to #[proc_macro_hack]",
+        ))
+    }
+}
+
+fn parse_export(attrs: TokenStream, vis: Visibility, tokens: Iter) -> Result<Export, Error> {
+    let _ = parse_punct(tokens, ':');
+    let _ = parse_punct(tokens, ':');
+    let from = parse_ident(tokens)?;
+    parse_punct(tokens, ':')?;
+    parse_punct(tokens, ':')?;
+
+    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();
+            loop {
+                macros.push(parse_macro(content)?);
+                if content.peek().is_none() {
+                    break;
+                }
+                parse_punct(content, ',')?;
+                if content.peek().is_none() {
+                    break;
+                }
+            }
+            tokens.next().unwrap();
+        }
+        _ => macros.push(parse_macro(tokens)?),
+    }
+
+    parse_punct(tokens, ';')?;
+    Ok(Export {
+        attrs,
+        vis,
+        from,
+        macros,
+    })
+}
+
+fn parse_punct(tokens: Iter, ch: char) -> Result<(), Error> {
+    match tokens.peek() {
+        Some(TokenTree::Punct(punct)) if punct.as_char() == ch => {
+            tokens.next().unwrap();
+            Ok(())
+        }
+        tt => Err(Error::new(
+            tt.map_or_else(Span::call_site, TokenTree::span),
+            format!("expected `{}`", ch),
+        )),
+    }
+}
+
+fn parse_define(
+    attrs: TokenStream,
+    vis: Visibility,
+    fn_token: Span,
+    tokens: Iter,
+) -> Result<Define, Error> {
+    if vis.is_none() {
+        return Err(Error::new(
+            fn_token,
+            "functions tagged with `#[proc_macro_hack]` must be `pub`",
+        ));
+    }
+    let name = parse_ident(tokens)?;
+    let body = tokens.collect();
+    Ok(Define { attrs, name, body })
+}
+
+fn parse_macro(tokens: Iter) -> Result<Macro, Error> {
+    let name = parse_ident(tokens)?;
+    let export_as = match tokens.peek() {
+        Some(TokenTree::Ident(ident)) if ident.to_string() == "as" => {
+            tokens.next().unwrap();
+            parse_ident(tokens)?
+        }
+        _ => name.clone(),
+    };
+    Ok(Macro { name, export_as })
+}
+
+fn parse_ident(tokens: Iter) -> Result<Ident, Error> {
+    match tokens.next() {
+        Some(TokenTree::Ident(ident)) => Ok(ident),
+        tt => Err(Error::new(
+            tt.as_ref().map_or_else(Span::call_site, TokenTree::span),
+            "expected identifier",
+        )),
+    }
+}
+
+fn parse_keyword(tokens: Iter, kw: &'static str) -> Result<(), Error> {
+    match &tokens.next() {
+        Some(TokenTree::Ident(ident)) if ident.to_string() == kw => Ok(()),
+        tt => Err(Error::new(
+            tt.as_ref().map_or_else(Span::call_site, TokenTree::span),
+            format!("expected `{}`", kw),
+        )),
+    }
+}
+
+fn parse_int(tokens: Iter) -> Result<u16, Span> {
+    match tokens.next() {
+        Some(TokenTree::Literal(lit)) => lit.to_string().parse().map_err(|_| lit.span()),
+        Some(tt) => Err(tt.span()),
+        None => Err(Span::call_site()),
+    }
+}
+
+fn parse_group(
+    tokens: Iter,
+    delimiter: Delimiter,
+) -> Result<Peekable<token_stream::IntoIter>, Error> {
+    match &tokens.next() {
+        Some(TokenTree::Group(group)) if group.delimiter() == delimiter => {
+            Ok(group.stream().into_iter().peekable())
+        }
+        tt => Err(Error::new(
+            tt.as_ref().map_or_else(Span::call_site, TokenTree::span),
+            "expected delimiter",
+        )),
+    }
+}
+
+fn parse_visibility(tokens: Iter) -> Result<Visibility, Error> {
+    if let Some(TokenTree::Ident(ident)) = tokens.peek() {
+        if ident.to_string() == "pub" {
+            return Ok(Some(tokens.next().unwrap().span()));
+        }
+    }
+    Ok(None)
+}
+
+fn parse_attributes(tokens: Iter) -> Result<TokenStream, Error> {
+    let mut attrs = TokenStream::new();
+    while let Some(TokenTree::Punct(punct)) = tokens.peek() {
+        if punct.as_char() != '#' {
+            break;
+        }
+        let span = punct.span();
+        attrs.extend(tokens.next());
+        match tokens.peek() {
+            Some(TokenTree::Group(group)) if group.delimiter() == Bracket => {
+                attrs.extend(tokens.next());
+            }
+            _ => return Err(Error::new(span, "unexpected input")),
+        }
+    }
+    Ok(attrs)
+}
+
+pub(crate) fn parse_export_args(tokens: Iter) -> Result<ExportArgs, Error> {
+    let mut args = ExportArgs {
+        support_nested: false,
+        internal_macro_calls: 0,
+        fake_call_site: false,
+    };
+
+    while let Some(tt) = tokens.next() {
+        match &tt {
+            TokenTree::Ident(ident) if ident.to_string() == "support_nested" => {
+                args.support_nested = true;
+            }
+            TokenTree::Ident(ident) if ident.to_string() == "internal_macro_calls" => {
+                parse_punct(tokens, '=')?;
+                let calls = parse_int(tokens).map_err(|span| {
+                    Error::new(span, "expected integer value for internal_macro_calls")
+                })?;
+                args.internal_macro_calls = calls;
+            }
+            TokenTree::Ident(ident) if ident.to_string() == "fake_call_site" => {
+                args.fake_call_site = true;
+            }
+            _ => {
+                return Err(Error::new(
+                    tt.span(),
+                    "expected one of: `support_nested`, `internal_macro_calls`, `fake_call_site`",
+                ))
+            }
+        }
+        if tokens.peek().is_none() {
+            break;
+        }
+        parse_punct(tokens, ',')?;
+    }
+
+    Ok(args)
+}
+
+pub(crate) fn parse_define_args(tokens: Iter) -> Result<(), Error> {
+    if tokens.peek().is_none() {
+        Ok(())
+    } else {
+        Err(Error::new(Span::call_site(), "unexpected input"))
+    }
+}
+
+pub(crate) fn parse_enum_hack(tokens: Iter) -> Result<TokenStream, Error> {
+    parse_keyword(tokens, "enum")?;
+    parse_ident(tokens)?;
+
+    let ref mut braces = parse_group(tokens, Brace)?;
+    parse_ident(braces)?;
+    parse_punct(braces, '=')?;
+
+    let ref mut parens = parse_group(braces, Parenthesis)?;
+    parse_ident(parens)?;
+    parse_punct(parens, '!')?;
+
+    let ref mut inner = parse_group(parens, Brace)?;
+    let token_stream = inner.collect();
+
+    parse_punct(parens, ',')?;
+    let _ = parens.next();
+    parse_punct(braces, '.')?;
+    let _ = braces.next();
+    parse_punct(braces, ',')?;
+
+    Ok(token_stream)
+}
+
+pub(crate) fn parse_fake_call_site(tokens: Iter) -> Result<FakeCallSite, Error> {
+    parse_punct(tokens, '#')?;
+    let ref mut attr = parse_group(tokens, Bracket)?;
+    parse_keyword(attr, "derive")?;
+    let ref mut path = parse_group(attr, Parenthesis)?;
+    Ok(FakeCallSite {
+        derive: parse_ident(path)?,
+        rest: tokens.collect(),
+    })
+}
diff --git a/src/quote.rs b/src/quote.rs
new file mode 100644
index 0000000..a3d648d
--- /dev/null
+++ b/src/quote.rs
@@ -0,0 +1,114 @@
+use proc_macro::{Ident, TokenStream, TokenTree};
+use std::iter;
+
+macro_rules! quote {
+    () => {
+        ::proc_macro::TokenStream::new()
+    };
+    ($($tt:tt)*) => {{
+        let mut tokens = ::proc_macro::TokenStream::new();
+        quote_each_token!(tokens $($tt)*);
+        tokens
+    }};
+}
+
+macro_rules! quote_each_token {
+    ($tokens:ident # $var:ident $($rest:tt)*) => {
+        $crate::quote::Tokens::extend(&mut $tokens, &$var);
+        quote_each_token!($tokens $($rest)*);
+    };
+    ($tokens:ident $ident:ident $($rest:tt)*) => {
+        <::proc_macro::TokenStream as ::std::iter::Extend<_>>::extend(
+            &mut $tokens,
+            ::std::iter::once(
+                ::proc_macro::TokenTree::Ident(
+                    ::proc_macro::Ident::new(
+                        stringify!($ident),
+                        ::proc_macro::Span::call_site(),
+                    ),
+                ),
+            ),
+        );
+        quote_each_token!($tokens $($rest)*);
+    };
+    ($tokens:ident ( $($inner:tt)* ) $($rest:tt)*) => {
+        <::proc_macro::TokenStream as ::std::iter::Extend<_>>::extend(
+            &mut $tokens,
+            ::std::iter::once(
+                ::proc_macro::TokenTree::Group(
+                    ::proc_macro::Group::new(
+                        ::proc_macro::Delimiter::Parenthesis,
+                        quote!($($inner)*),
+                    ),
+                ),
+            ),
+        );
+        quote_each_token!($tokens $($rest)*);
+    };
+    ($tokens:ident [ $($inner:tt)* ] $($rest:tt)*) => {
+        <::proc_macro::TokenStream as ::std::iter::Extend<_>>::extend(
+            &mut $tokens,
+            ::std::iter::once(
+                ::proc_macro::TokenTree::Group(
+                    ::proc_macro::Group::new(
+                        ::proc_macro::Delimiter::Bracket,
+                        quote!($($inner)*),
+                    ),
+                ),
+            ),
+        );
+        quote_each_token!($tokens $($rest)*);
+    };
+    ($tokens:ident { $($inner:tt)* } $($rest:tt)*) => {
+        <::proc_macro::TokenStream as ::std::iter::Extend<_>>::extend(
+            &mut $tokens,
+            ::std::iter::once(
+                ::proc_macro::TokenTree::Group(
+                    ::proc_macro::Group::new(
+                        ::proc_macro::Delimiter::Brace,
+                        quote!($($inner)*),
+                    ),
+                ),
+            ),
+        );
+        quote_each_token!($tokens $($rest)*);
+    };
+    ($tokens:ident $punct:tt $($rest:tt)*) => {
+        <::proc_macro::TokenStream as ::std::iter::Extend<_>>::extend(
+            &mut $tokens,
+            stringify!($punct).parse::<::proc_macro::TokenStream>(),
+        );
+        quote_each_token!($tokens $($rest)*);
+    };
+    ($tokens:ident) => {};
+}
+
+pub trait Tokens {
+    fn extend(tokens: &mut TokenStream, var: &Self);
+}
+
+impl Tokens for Ident {
+    fn extend(tokens: &mut TokenStream, var: &Self) {
+        tokens.extend(iter::once(TokenTree::Ident(var.clone())));
+    }
+}
+
+impl Tokens for TokenStream {
+    fn extend(tokens: &mut TokenStream, var: &Self) {
+        tokens.extend(var.clone());
+    }
+}
+
+impl<T: Tokens> Tokens for Option<T> {
+    fn extend(tokens: &mut TokenStream, var: &Self) {
+        if let Some(var) = var {
+            T::extend(tokens, var);
+        }
+    }
+}
+
+impl<T: Tokens> Tokens for &T {
+    fn extend(tokens: &mut TokenStream, var: &Self) {
+        T::extend(tokens, var);
+    }
+}
diff --git a/tests/compiletest.rs b/tests/compiletest.rs
new file mode 100644
index 0000000..f9aea23
--- /dev/null
+++ b/tests/compiletest.rs
@@ -0,0 +1,6 @@
+#[rustversion::attr(not(nightly), ignore)]
+#[test]
+fn ui() {
+    let t = trybuild::TestCases::new();
+    t.compile_fail("tests/ui/*.rs");
+}
diff --git a/tests/ui/private.rs b/tests/ui/private.rs
new file mode 100644
index 0000000..1ab8444
--- /dev/null
+++ b/tests/ui/private.rs
@@ -0,0 +1,8 @@
+use proc_macro_hack::proc_macro_hack;
+
+#[proc_macro_hack]
+fn my_macro(input: TokenStream) -> TokenStream {
+    unimplemented!()
+}
+
+fn main() {}
diff --git a/tests/ui/private.stderr b/tests/ui/private.stderr
new file mode 100644
index 0000000..be79443
--- /dev/null
+++ b/tests/ui/private.stderr
@@ -0,0 +1,5 @@
+error: functions tagged with `#[proc_macro_hack]` must be `pub`
+ --> $DIR/private.rs:4:1
+  |
+4 | fn my_macro(input: TokenStream) -> TokenStream {
+  | ^^
diff --git a/tests/ui/unexpected.rs b/tests/ui/unexpected.rs
new file mode 100644
index 0000000..122ded5
--- /dev/null
+++ b/tests/ui/unexpected.rs
@@ -0,0 +1,6 @@
+use proc_macro_hack::proc_macro_hack;
+
+#[proc_macro_hack]
+pub struct What;
+
+fn main() {}
diff --git a/tests/ui/unexpected.stderr b/tests/ui/unexpected.stderr
new file mode 100644
index 0000000..e3da97a
--- /dev/null
+++ b/tests/ui/unexpected.stderr
@@ -0,0 +1,5 @@
+error: unexpected input to #[proc_macro_hack]
+ --> $DIR/unexpected.rs:4:5
+  |
+4 | pub struct What;
+  |     ^^^^^^
diff --git a/tests/ui/unknown-arg.rs b/tests/ui/unknown-arg.rs
new file mode 100644
index 0000000..aa9b82c
--- /dev/null
+++ b/tests/ui/unknown-arg.rs
@@ -0,0 +1,6 @@
+use proc_macro_hack::proc_macro_hack;
+
+#[proc_macro_hack(fake_call_site, support_nexted)]
+pub use demo::some_macro;
+
+fn main() {}
diff --git a/tests/ui/unknown-arg.stderr b/tests/ui/unknown-arg.stderr
new file mode 100644
index 0000000..d3cd8c9
--- /dev/null
+++ b/tests/ui/unknown-arg.stderr
@@ -0,0 +1,5 @@
+error: expected one of: `support_nested`, `internal_macro_calls`, `fake_call_site`
+ --> $DIR/unknown-arg.rs:3:35
+  |
+3 | #[proc_macro_hack(fake_call_site, support_nexted)]
+  |                                   ^^^^^^^^^^^^^^