diff --git a/examples/subclass/build.rs b/examples/subclass/build.rs
new file mode 100644
index 0000000..b41e924
--- /dev/null
+++ b/examples/subclass/build.rs
@@ -0,0 +1,93 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() -> miette::Result<()> {
+    let path = std::path::PathBuf::from("src");
+    let mut b = autocxx_build::Builder::new("src/main.rs", &[&path])
+        .auto_allowlist(true)
+        .build()?;
+    b.flag_if_supported("-std=c++17")
+        .file("src/messages.cc")
+        .compile("autocxx-subclass-example");
+    println!("cargo:rerun-if-changed=src/main.rs");
+    println!("cargo:rerun-if-changed=src/messages.cc");
+    println!("cargo:rerun-if-changed=src/messages.h");
+
+    // The following line is *unrelated* to autocxx builds and is
+    // just designed to ensure that example code doesn't get out of sync
+    // from copies in comments.
+    ensure_comments_match_real_code(&std::path::PathBuf::from("src/main.rs"));
+    Ok(())
+}
+
+use std::fs::File;
+use std::io::BufRead;
+use std::io::BufReader;
+use std::io::Lines;
+use std::path::Path;
+
+enum CommentMatcherState {
+    Searching,
+    EatingBacktickLine(Lines<BufReader<File>>),
+    SearchingForFirstLine(Lines<BufReader<File>>),
+    Found(Lines<BufReader<File>>),
+}
+
+fn ensure_comments_match_real_code(rs_file: &Path) {
+    use regex::Regex;
+    let start_re = Regex::new(r"// .*from ([\w/]+\.\w+).*").unwrap();
+    let strip_comment_re = Regex::new(r"// (.*)").unwrap();
+    let file = File::open(rs_file).unwrap();
+    let lines = BufReader::new(file).lines();
+    let mut state = CommentMatcherState::Searching;
+    for line in lines {
+        let line = line.unwrap();
+        state = match state {
+            CommentMatcherState::Searching => match start_re.captures(&line) {
+                Some(captures) => {
+                    let fname = captures.get(1).unwrap().as_str();
+                    let srcfile = File::open(fname).unwrap();
+                    let srclines = BufReader::new(srcfile).lines();
+                    CommentMatcherState::EatingBacktickLine(srclines)
+                }
+                None => CommentMatcherState::Searching,
+            },
+            CommentMatcherState::EatingBacktickLine(srclines) => {
+                CommentMatcherState::SearchingForFirstLine(srclines)
+            }
+            CommentMatcherState::SearchingForFirstLine(mut srclines) => {
+                match strip_comment_re.captures(&line) {
+                    Some(captures) => {
+                        let mut found = false;
+                        while !found {
+                            let srcline = srclines.next().unwrap().unwrap();
+                            found = captures.get(1).unwrap().as_str() == srcline;
+                        }
+                        CommentMatcherState::Found(srclines)
+                    }
+                    None => CommentMatcherState::Searching,
+                }
+            }
+            CommentMatcherState::Found(mut srclines) => {
+                if line == "// ```" {
+                    CommentMatcherState::Searching
+                } else {
+                    match strip_comment_re.captures(&line) {
+                        Some(captures) => {
+                            let actual = captures.get(1).unwrap().as_str();
+                            let expected = srclines.next().unwrap().unwrap();
+                            assert_eq!(expected, actual);
+                            CommentMatcherState::Found(srclines)
+                        }
+                        None => CommentMatcherState::Searching,
+                    }
+                }
+            }
+        }
+    }
+}