diff --git a/Cargo.toml b/Cargo.toml
index 5527c5d..da1c1e0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "proc-macro2"
-version = "0.4.22" # remember to update html_root_url
+version = "0.4.23" # remember to update html_root_url
 authors = ["Alex Crichton <alex@alexcrichton.com>"]
 license = "MIT/Apache-2.0"
 readme = "README.md"
diff --git a/build.rs b/build.rs
index 3379da3..784c59c 100644
--- a/build.rs
+++ b/build.rs
@@ -27,6 +27,8 @@
 
         if cfg!(procmacro2_semver_exempt) {
             println!("cargo:rustc-cfg=super_unstable");
+            // https://github.com/alexcrichton/proc-macro2/issues/147
+            println!("cargo:rustc-cfg=procmacro2_semver_exempt");
         }
     }
 
diff --git a/src/lib.rs b/src/lib.rs
index 85fe514..2f632f6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -43,7 +43,7 @@
 //! [ts]: https://doc.rust-lang.org/proc_macro/struct.TokenStream.html
 
 // Proc-macro2 types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/proc-macro2/0.4.22")]
+#![doc(html_root_url = "https://docs.rs/proc-macro2/0.4.23")]
 #![cfg_attr(
     super_unstable,
     feature(proc_macro_raw_ident, proc_macro_span, proc_macro_def_site)