diff --git a/README.md b/README.md
index ae8ab27..fe7673f 100644
--- a/README.md
+++ b/README.md
@@ -15,6 +15,10 @@ See [`examples/rand-infer.rs`](examples/rand-infer.rs).
 echo '"def helloworl"' | cargo run --example rand-infer
 ```
 
+```sh
+echo '"def hellowor<unk>l"' | cargo run --example rand-infer
+```
+
 ## TODOs
 
 - [ ] Python bindings
diff --git a/examples/rand-infer.rs b/examples/rand-infer.rs
index 224ac72..30efc1a 100644
--- a/examples/rand-infer.rs
+++ b/examples/rand-infer.rs
@@ -124,6 +124,15 @@ fn build_vocab<T: AsRef<Tokenizer>>(tokenizer: T) -> Result<Vec<Vec<u8>>> {
         match parse_byte_repr(token) {
             Ok(byte) => token_bytes[id as usize].push(byte),
             Err(_) => {
+                if tokenizer
+                    .get_added_vocabulary()
+                    .get_added_tokens_decoder()
+                    .contains_key(&id)
+                {
+                    // ignore special tokens
+                    continue;
+                }
+
                 let decoded = tokenizer
                     .decode(&[dummy_token_id, id, dummy_token_id], false)
                     .map_err(|e| eyre!(e))?;
@@ -167,6 +176,24 @@ async fn main_body() -> Result<()> {
         .decode(tokenized.get_ids(), false)
         .map_err(|e| eyre!(e))?;
 
+    let offset = tokenized
+        .get_ids()
+        .iter()
+        .filter_map(|&id| {
+            tokenizer
+                .get_added_vocabulary()
+                .get_added_tokens_decoder()
+                .get(&id)
+        })
+        .last()
+        .and_then(|special_token| {
+            println!("{special_token:?}");
+            text.rfind(&special_token.content)
+                .map(|pos| pos + special_token.content.len())
+        })
+        .unwrap_or(0);
+    println!("search from pos {offset}\n");
+
     let Some((tree, mut req)) = SearchTree::new(
         automaton.clone(),
         |end_pos| async {
@@ -178,7 +205,7 @@ async fn main_body() -> Result<()> {
             Ok::<_, tokenizers::Error>(res)
         },
         text.as_str(),
-        0,
+        offset,
     )
     .await
     .map_err(|e| eyre!(e))?