diff --git a/lib/tiktoken.ex b/lib/tiktoken.ex
index 14a0fe7..a611ecf 100644
--- a/lib/tiktoken.ex
+++ b/lib/tiktoken.ex
@@ -7,7 +7,8 @@ defmodule Tiktoken do
     "p50k_base" => Tiktoken.P50K,
     "p50k_edit" => Tiktoken.P50KEdit,
     "r50k_base" => Tiktoken.R50K,
-    "cl100k_base" => Tiktoken.CL100K
+    "cl100k_base" => Tiktoken.CL100K,
+    "o200k_base" => Tiktoken.O200K
   }
 
   def encoding_for_model(model) do
diff --git a/lib/tiktoken/native.ex b/lib/tiktoken/native.ex
index a41de1d..8ebdf8a 100644
--- a/lib/tiktoken/native.ex
+++ b/lib/tiktoken/native.ex
@@ -32,6 +32,11 @@ defmodule Tiktoken.Native do
   def cl100k_encode_with_special_tokens(_input), do: err()
   def cl100k_decode(_ids), do: err()
 
+  def o200k_encode_ordinary(_input), do: err()
+  def o200k_encode(_input, _allowed_special), do: err()
+  def o200k_encode_with_special_tokens(_input), do: err()
+  def o200k_decode(_ids), do: err()
+
   def context_size_for_model(_model), do: err()
 
   defp err, do: :erlang.nif_error(:nif_not_loaded)
diff --git a/lib/tiktoken/o200k.ex b/lib/tiktoken/o200k.ex
new file mode 100644
index 0000000..030de90
--- /dev/null
+++ b/lib/tiktoken/o200k.ex
@@ -0,0 +1,23 @@
+defmodule Tiktoken.O200K do
+  @behaviour Tiktoken.Encoding
+
+  @impl Tiktoken.Encoding
+  def encode_ordinary(text) do
+    Tiktoken.Native.o200k_encode_ordinary(text)
+  end
+
+  @impl Tiktoken.Encoding
+  def encode(text, allowed_special \\ []) do
+    Tiktoken.Native.o200k_encode(text, allowed_special)
+  end
+
+  @impl Tiktoken.Encoding
+  def encode_with_special_tokens(text) do
+    Tiktoken.Native.o200k_encode_with_special_tokens(text)
+  end
+
+  @impl Tiktoken.Encoding
+  def decode(ids) do
+    Tiktoken.Native.o200k_decode(ids)
+  end
+end
diff --git a/native/tiktoken/Cargo.lock b/native/tiktoken/Cargo.lock
index 6e888fd..3140b1f 100644
--- a/native/tiktoken/Cargo.lock
+++ b/native/tiktoken/Cargo.lock
@@ -79,9 +79,9 @@ dependencies = [
 
 [[package]]
 name = "heck"
-version = "0.4.1"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8"
+checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"
 
 [[package]]
 name = "lazy_static"
@@ -204,20 +204,19 @@ checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
 
 [[package]]
 name = "rustler"
-version = "0.31.0"
+version = "0.33.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a75d458f38f550976d0e4b347ca57241c192019777e46af7af73b27783287088"
+checksum = "45d51ae0239c57c3a3e603dd855ace6795078ef33c95c85d397a100ac62ed352"
 dependencies = [
- "lazy_static",
  "rustler_codegen",
  "rustler_sys",
 ]
 
 [[package]]
 name = "rustler_codegen"
-version = "0.31.0"
+version = "0.33.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dbd46408f51c0ca6a68dc36aa4f90e3554960bd1b7cc513e6ff2ccad7dd92aff"
+checksum = "27061f1a2150ad64717dca73902678c124b0619b0d06563294df265bc84759e1"
 dependencies = [
  "heck",
  "proc-macro2",
@@ -227,9 +226,9 @@ dependencies = [
 
 [[package]]
 name = "rustler_sys"
-version = "2.3.2"
+version = "2.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ff76ba8524729d7c9db2b3e80f2269d1fdef39b5a60624c33fd794797e69b558"
+checksum = "2062df0445156ae93cf695ef38c00683848d956b30507592143c01fe8fb52fda"
 dependencies = [
  "regex",
  "unreachable",
@@ -274,9 +273,9 @@ dependencies = [
 
 [[package]]
 name = "tiktoken-rs"
-version = "0.5.8"
+version = "0.5.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "40894b788eb28bbb7e36bdc8b7b1b1488b9c93fa3730f315ab965330c94c0842"
+checksum = "c314e7ce51440f9e8f5a497394682a57b7c323d0f4d0a6b1b13c429056e0e234"
 dependencies = [
  "anyhow",
  "base64",
diff --git a/native/tiktoken/Cargo.toml b/native/tiktoken/Cargo.toml
index b630fa3..88185da 100644
--- a/native/tiktoken/Cargo.toml
+++ b/native/tiktoken/Cargo.toml
@@ -10,5 +10,5 @@ path = "src/lib.rs"
 crate-type = ["cdylib"]
 
 [dependencies]
-rustler = "0.31.0"
-tiktoken-rs = "0.5.8"
+rustler = "0.33.0"
+tiktoken-rs = "0.5.9"
diff --git a/native/tiktoken/src/lib.rs b/native/tiktoken/src/lib.rs
index 3a3defd..4d37c7b 100644
--- a/native/tiktoken/src/lib.rs
+++ b/native/tiktoken/src/lib.rs
@@ -4,6 +4,7 @@ use std::vec::Vec;
 #[rustler::nif]
 fn encoding_for_model(model: &str) -> Option<&str> {
     match tiktoken_rs::tokenizer::get_tokenizer(model) {
+        Some(tiktoken_rs::tokenizer::Tokenizer::O200kBase) => Some("o200k_base"),
         Some(tiktoken_rs::tokenizer::Tokenizer::Cl100kBase) => Some("cl100k_base"),
         Some(tiktoken_rs::tokenizer::Tokenizer::P50kBase) => Some("p50k_base"),
         Some(tiktoken_rs::tokenizer::Tokenizer::R50kBase) => Some("r50k_base"),
@@ -185,6 +186,48 @@ fn context_size_for_model(model: &str) -> usize {
     tiktoken_rs::model::get_context_size(model)
 }
 
+// o200k
+
+#[rustler::nif]
+fn o200k_encode_ordinary(text: &str) -> Result<Vec<usize>, String> {
+    let bpe = tiktoken_rs::o200k_base_singleton();
+    {
+        let guard = bpe.lock();
+        Ok(guard.encode_ordinary(text))
+    }
+}
+
+#[rustler::nif]
+fn o200k_encode(text: &str, allowed_special: Vec<&str>) -> Result<Vec<usize>, String> {
+    let set = HashSet::from_iter(allowed_special.iter().cloned());
+    let bpe = tiktoken_rs::o200k_base_singleton();
+    {
+        let guard = bpe.lock();
+        Ok(guard.encode(text, set))
+    }
+}
+
+#[rustler::nif]
+fn o200k_encode_with_special_tokens(text: &str) -> Result<Vec<usize>, String> {
+    let bpe = tiktoken_rs::o200k_base_singleton();
+    {
+        let guard = bpe.lock();
+        Ok(guard.encode_with_special_tokens(text))
+    }
+}
+
+#[rustler::nif]
+fn o200k_decode(ids: Vec<usize>) -> Result<String, String> {
+    let bpe = tiktoken_rs::o200k_base_singleton();
+    {
+        let guard = bpe.lock();
+        match guard.decode(ids) {
+            Ok(text) => Ok(text),
+            Err(e) => Err(e.to_string()),
+        }
+    }
+}
+
 rustler::init!(
     "Elixir.Tiktoken.Native",
     [
@@ -205,6 +248,10 @@ rustler::init!(
         cl100k_encode,
         cl100k_encode_with_special_tokens,
         cl100k_decode,
+        o200k_encode_ordinary,
+        o200k_encode,
+        o200k_encode_with_special_tokens,
+        o200k_decode,
         context_size_for_model
     ]
 );