diff --git a/Cargo.lock b/Cargo.lock
index 8aba7f7..ea6b305 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4,18 +4,18 @@ version = 4
 
 [[package]]
 name = "aho-corasick"
-version = "1.1.3"
+version = "1.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e60d3430d3a69478ad0993f19238d2df97c507009a52b3c10addcd7f6bcb916"
+checksum = "ddd31a130427c27518df266943a5308ed92d4b226cc639f5a8f1002816174301"
 dependencies = [
  "memchr",
 ]
 
 [[package]]
 name = "anyhow"
-version = "1.0.99"
+version = "1.0.100"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b0674a1ddeecb70197781e945de4b3b8ffb61fa939a5597bcf48503737663100"
+checksum = "a23eb6b1614318a8071c9b2521f36b424b2c83db5eb3a0fead4a6c0809af6e61"
 
 [[package]]
 name = "base64"
@@ -60,15 +60,15 @@ checksum = "349f9b6a179ed607305526ca489b34ad0a41aed5f7980fa90eb03160b69598fb"
 
 [[package]]
 name = "bitflags"
-version = "2.9.3"
+version = "2.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "34efbcccd345379ca2868b2b2c9d3782e9cc58ba87bc7d79d5b53d9c9ae6f25d"
+checksum = "812e12b5285cc515a9c72a5c1d3b6d46a19dac5acfef5265968c166106e31dd3"
 
 [[package]]
 name = "bstr"
-version = "1.12.0"
+version = "1.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "234113d19d0d7d613b40e86fb654acf958910802bcceab913a4f9e7cda03b1a4"
+checksum = "63044e1ae8e69f3b5a92c736ca6269b8d12fa7efe39bf34ddb06d102cf0e2cab"
 dependencies = [
  "memchr",
  "regex-automata",
@@ -86,9 +86,9 @@ dependencies = [
 
 [[package]]
 name = "cfg-if"
-version = "1.0.3"
+version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2fd1289c04a9ea8cb22300a459a72a385d7c73d3259e2ed7dcb2af674838cfa9"
+checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
 [[package]]
 name = "clang-sys"
@@ -147,18 +147,18 @@ checksum = "830d08ce1d1d941e6b30645f1a0eb5643013d835ce3779a5fc208261dbe10f55"
 
 [[package]]
 name = "libc"
-version = "0.2.175"
+version = "0.2.177"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6a82ae493e598baaea5209805c49bbf2ea7de956d50d7da0da1164f9c6d28543"
+checksum = "2874a2af47a2325c2001a6e6fad9b16a53b802102b528163885171cf92b15976"
 
 [[package]]
 name = "libloading"
-version = "0.8.8"
+version = "0.8.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "07033963ba89ebaf1584d767badaa2e8fcec21aedea6b8c0346d487d49c28667"
+checksum = "d7c4b02199fee7c5d21a5ae7d8cfa79a6ef5bb2fc834d6e9058e89c825efdc55"
 dependencies = [
  "cfg-if",
- "windows-targets",
+ "windows-link",
 ]
 
 [[package]]
@@ -186,9 +186,9 @@ dependencies = [
 
 [[package]]
 name = "memchr"
-version = "2.7.5"
+version = "2.7.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32a282da65faaf38286cf3be983213fcf1d2e2a58700e808f83f4ea9a4804bc0"
+checksum = "f52b00d39961fc5b2736ea853c9cc86238e165017a493d1d5c8eac6bdc4cc273"
 
 [[package]]
 name = "minimal-lexical"
@@ -208,18 +208,18 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.101"
+version = "1.0.103"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "89ae43fd86e4158d6db51ad8e2b80f313af9cc74f5c0e03ccb87de09998732de"
+checksum = "5ee95bc4ef87b8d5ba32e8b7714ccc834865276eab0aed5c9958d00ec45f49e8"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.40"
+version = "1.0.42"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1885c039570dc00dcb4ff087a89e185fd56bae234ddc7f056a945bf36467248d"
+checksum = "a338cc41d27e6cc6dce6cefc13a0729dfbb81c262b1f519331575dd80ef3067f"
 dependencies = [
  "proc-macro2",
 ]
@@ -256,9 +256,9 @@ checksum = "08f8d2924cf136a1315e2b4c7460a39f62ef11ee5d522df9b2750fab55b868b6"
 
 [[package]]
 name = "regex"
-version = "1.11.2"
+version = "1.12.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "23d7fd106d8c02486a8d64e778353d1cffe08ce79ac2e82f540c86d0facf6912"
+checksum = "843bc0191f75f3e22651ae5f1e72939ab2f72a4bc30fa80a066bd66edefc24d4"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -268,9 +268,9 @@ dependencies = [
 
 [[package]]
 name = "regex-automata"
-version = "0.4.10"
+version = "0.4.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6b9458fa0bfeeac22b5ca447c63aaf45f28439a709ccd244698632f9aa6394d6"
+checksum = "5276caf25ac86c8d810222b3dbb938e512c55c6831a10f3e6ed1c93b84041f1c"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -279,9 +279,9 @@ dependencies = [
 
 [[package]]
 name = "regex-syntax"
-version = "0.8.6"
+version = "0.8.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "caf4aa5b0f434c91fe5c7f1ecb6a5ece2130b02ad2a590589dda5146df959001"
+checksum = "7a2d987857b319362043e95f5353c0535c1f58eec5336fdfcf626430af7def58"
 
 [[package]]
 name = "rustc-hash"
@@ -297,18 +297,27 @@ checksum = "1bc711410fbe7399f390ca1c3b60ad0f53f80e95c5eb935e52268a0e2cd49acc"
 
 [[package]]
 name = "serde"
-version = "1.0.219"
+version = "1.0.228"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a8e94ea7f378bd32cbbd37198a4a91436180c5bb472411e48b5ec2e2124ae9e"
+dependencies = [
+ "serde_core",
+]
+
+[[package]]
+name = "serde_core"
+version = "1.0.228"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5f0e2c6ed6606019b4e29e69dbaba95b11854410e5347d525002456dbbb786b6"
+checksum = "41d385c7d4ca58e59fc732af25c3983b67ac852c1a25000afe1175de458b67ad"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.219"
+version = "1.0.228"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b0276cf7f2c73365f7157c8123c21cd9a50fbbd844757af28ca1f5925fc2a00"
+checksum = "d540f220d3187173da220f885ab66608367b6574e925011a9353e4badda91d79"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -329,9 +338,9 @@ checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
 
 [[package]]
 name = "syn"
-version = "2.0.106"
+version = "2.0.110"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ede7c438028d4436d71104916910f5bb611972c5cfd7f89b8300a8186e6fada6"
+checksum = "a99801b5bd34ede4cf3fc688c5919368fea4e4814a4664359503e6015b280aea"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -340,9 +349,9 @@ dependencies = [
 
 [[package]]
 name = "tiktoken-rs"
-version = "0.7.0"
+version = "0.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "25563eeba904d770acf527e8b370fe9a5547bacd20ff84a0b6c3bc41288e5625"
+checksum = "3a19830747d9034cd9da43a60eaa8e552dfda7712424aebf187b7a60126bae0d"
 dependencies = [
  "anyhow",
  "base64",
@@ -364,77 +373,12 @@ dependencies = [
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.18"
+version = "1.0.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"
+checksum = "9312f7c4f6ff9069b165498234ce8be658059c6728633667c526e27dc2cf1df5"
 
 [[package]]
 name = "windows-link"
-version = "0.1.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e6ad25900d524eaabdbbb96d20b4311e1e7ae1699af4fb28c17ae66c80d798a"
-
-[[package]]
-name = "windows-targets"
-version = "0.53.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d5fe6031c4041849d7c496a8ded650796e7b6ecc19df1a431c1a363342e5dc91"
-dependencies = [
- "windows-link",
- "windows_aarch64_gnullvm",
- "windows_aarch64_msvc",
- "windows_i686_gnu",
- "windows_i686_gnullvm",
- "windows_i686_msvc",
- "windows_x86_64_gnu",
- "windows_x86_64_gnullvm",
- "windows_x86_64_msvc",
-]
-
-[[package]]
-name = "windows_aarch64_gnullvm"
-version = "0.53.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "86b8d5f90ddd19cb4a147a5fa63ca848db3df085e25fee3cc10b39b6eebae764"
-
-[[package]]
-name = "windows_aarch64_msvc"
-version = "0.53.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7651a1f62a11b8cbd5e0d42526e55f2c99886c77e007179efff86c2b137e66c"
-
-[[package]]
-name = "windows_i686_gnu"
-version = "0.53.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c1dc67659d35f387f5f6c479dc4e28f1d4bb90ddd1a5d3da2e5d97b42d6272c3"
-
-[[package]]
-name = "windows_i686_gnullvm"
-version = "0.53.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9ce6ccbdedbf6d6354471319e781c0dfef054c81fbc7cf83f338a4296c0cae11"
-
-[[package]]
-name = "windows_i686_msvc"
-version = "0.53.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "581fee95406bb13382d2f65cd4a908ca7b1e4c2f1917f143ba16efe98a589b5d"
-
-[[package]]
-name = "windows_x86_64_gnu"
-version = "0.53.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2e55b5ac9ea33f2fc1716d1742db15574fd6fc8dadc51caab1c16a3d3b4190ba"
-
-[[package]]
-name = "windows_x86_64_gnullvm"
-version = "0.53.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0a6e035dd0599267ce1ee132e51c27dd29437f63325753051e71dd9e42406c57"
-
-[[package]]
-name = "windows_x86_64_msvc"
-version = "0.53.0"
+version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "271414315aff87387382ec3d271b52d7ae78726f5d44ac98b4f4030c91880486"
+checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"
diff --git a/Gemfile.lock b/Gemfile.lock
index 566fe2d..84720c0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    tiktoken_ruby (0.0.12)
+    tiktoken_ruby (0.0.13)
       rb_sys (~> 0.9)
 
 GEM
diff --git a/ext/tiktoken_ruby/Cargo.toml b/ext/tiktoken_ruby/Cargo.toml
index eabeb46..70aa507 100644
--- a/ext/tiktoken_ruby/Cargo.toml
+++ b/ext/tiktoken_ruby/Cargo.toml
@@ -12,4 +12,4 @@ crate-type = ["cdylib"]
 [dependencies]
 magnus = { version = "0.8.2" }
 rb-sys = { version = "0.9.117", features = ["stable-api-compiled-fallback"] }
-tiktoken-rs = { version = "0.7.0" }
+tiktoken-rs = { version = "0.9.0" }
diff --git a/ext/tiktoken_ruby/src/lib.rs b/ext/tiktoken_ruby/src/lib.rs
index 8ddf5d3..102186b 100644
--- a/ext/tiktoken_ruby/src/lib.rs
+++ b/ext/tiktoken_ruby/src/lib.rs
@@ -25,12 +25,20 @@ fn o200k_base() -> CoreBPEWrapper {
     CoreBPEWrapper::new(core_bpe)
 }
 
+fn o200k_harmony() -> CoreBPEWrapper {
+    let core_bpe = tiktoken_rs::o200k_harmony().unwrap();
+    CoreBPEWrapper::new(core_bpe)
+}
+
 fn module() -> Result<RModule, magnus::Error> {
     Ruby::get().unwrap().define_module("Tiktoken")
 }
 
 fn uncicode_error() -> Result<ExceptionClass, magnus::Error> {
-    module()?.define_error("UnicodeError", Ruby::get().unwrap().exception_standard_error())
+    module()?.define_error(
+        "UnicodeError",
+        Ruby::get().unwrap().exception_standard_error(),
+    )
 }
 
 #[magnus::init]
@@ -43,6 +51,7 @@ fn init() -> Result<(), Error> {
     factory_module.define_singleton_method("p50k_edit", function!(p50k_edit, 0))?;
     factory_module.define_singleton_method("cl100k_base", function!(cl100k_base, 0))?;
     factory_module.define_singleton_method("o200k_base", function!(o200k_base, 0))?;
+    factory_module.define_singleton_method("o200k_harmony", function!(o200k_harmony, 0))?;
 
     let ext_module = module.define_module("Ext")?;
     let bpe_class = ext_module.define_class("CoreBPE", Ruby::get().unwrap().class_object())?;
diff --git a/lib/tiktoken_ruby.rb b/lib/tiktoken_ruby.rb
index 6372218..31c5465 100644
--- a/lib/tiktoken_ruby.rb
+++ b/lib/tiktoken_ruby.rb
@@ -65,7 +65,8 @@ def list_model_names
       :p50k_base,
       :p50k_edit,
       :cl100k_base,
-      :o200k_base
+      :o200k_base,
+      :o200k_harmony
     ]
 
     # taken from the python library here https://github.com/openai/tiktoken/blob/main/tiktoken/model.py
@@ -143,6 +144,7 @@ def list_model_names
       "gpt-4-": "cl100k_base",  # e.g., gpt-4-0314, etc., plus gpt-4-32k
       "gpt-3.5-turbo-": "cl100k_base",  # e.g, gpt-3.5-turbo-0301, -0401, etc.
       "gpt-35-turbo-": "cl100k_base",  # Azure deployment name
+      "gpt-oss-": "o200k_harmony",
       # fine-tuned
       "ft:gpt-4o": "cl100k_base",
       "ft:gpt-4": "cl100k_base",
diff --git a/lib/tiktoken_ruby/version.rb b/lib/tiktoken_ruby/version.rb
index c9ca723..c202097 100644
--- a/lib/tiktoken_ruby/version.rb
+++ b/lib/tiktoken_ruby/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Tiktoken
-  VERSION = "0.0.12"
+  VERSION = "0.0.13"
 end