---
 src/lib.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git b/src/lib.rs a/src/lib.rs
index d3eab1a0..8a9561ba 100644
--- b/src/lib.rs
+++ a/src/lib.rs
@@ -1,3 +1,4 @@
+extern crate proc_macro;
 use proc_macro::TokenStream;
 use proc_macro2::{Group, TokenStream as TokenStream2, TokenTree};
 use quote::quote;