diff --git a/Cargo.lock b/Cargo.lock
index cbfdcfd..d9c1f73 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -36,7 +36,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "regex",
- "rustc-hash 2.1.2",
+ "rustc-hash",
  "shlex",
  "syn",
 ]
@@ -218,18 +218,18 @@ dependencies = [
 
 [[package]]
 name = "rb-sys"
-version = "0.9.127"
+version = "0.9.128"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d7d7c9560fe42dcffa576941394075f18a17dce89fcf718a2fa90b7dc2134d12"
+checksum = "45ca28513560e56cfb79a62b1fce363c73af170a182024ce880c77ee9429920a"
 dependencies = [
  "rb-sys-build",
 ]
 
 [[package]]
 name = "rb-sys-build"
-version = "0.9.127"
+version = "0.9.128"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f1688e8f32967ba48c89e4dfa283b57f901075f542fc7ee9c3d7c5f9091ca1d9"
+checksum = "ce04b2c55eff3a21aaa623fcc655d94373238e72cac6b3e1a3641ff31649f99a"
 dependencies = [
  "bindgen",
  "lazy_static",
@@ -275,12 +275,6 @@ version = "0.8.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7a2d987857b319362043e95f5353c0535c1f58eec5336fdfcf626430af7def58"
 
-[[package]]
-name = "rustc-hash"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
-
 [[package]]
 name = "rustc-hash"
 version = "2.1.2"
@@ -347,9 +341,9 @@ dependencies = [
 
 [[package]]
 name = "tiktoken-rs"
-version = "0.11.0"
+version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fac4a168cfc1d8ed65bf17a6ee0843ad9a68f863c63c0fb2fa7eab67838782ee"
+checksum = "027853bbf8c7763b77c5c595f1c271c7d536ced7d6f83452911b944621e57fc2"
 dependencies = [
  "anyhow",
  "base64",
@@ -357,7 +351,7 @@ dependencies = [
  "fancy-regex",
  "lazy_static",
  "regex",
- "rustc-hash 1.1.0",
+ "rustc-hash",
 ]
 
 [[package]]
diff --git a/ext/tiktoken_ruby/Cargo.toml b/ext/tiktoken_ruby/Cargo.toml
index 004fea7..27b1f84 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 = "0.9.127", features = ["stable-api-compiled-fallback"] }
-tiktoken-rs = { version = "0.11.0" }
+tiktoken-rs = { version = "0.12.0" }
diff --git a/ext/tiktoken_ruby/src/core_bpe_wrapper.rs b/ext/tiktoken_ruby/src/core_bpe_wrapper.rs
index c054ff6..5feded7 100644
--- a/ext/tiktoken_ruby/src/core_bpe_wrapper.rs
+++ b/ext/tiktoken_ruby/src/core_bpe_wrapper.rs
@@ -20,7 +20,7 @@ struct EncodeData {
     core_bpe: *const tiktoken_rs::CoreBPE,
     text: String,
     allowed_special: HashSet<String>,
-    result: Vec<Rank>,
+    result: Result<Vec<Rank>, String>,
 }
 
 struct EncodeSpecialData {
@@ -46,7 +46,11 @@ unsafe extern "C" fn encode_without_gvl(data: *mut c_void) -> *mut c_void {
     let data = &mut *(data as *mut EncodeData);
     let core_bpe = &*data.core_bpe;
     let allowed_special: HashSet<&str> = data.allowed_special.iter().map(|s| s.as_str()).collect();
-    data.result = core_bpe.encode(&data.text, &allowed_special).0;
+    // Keep only the token vector and surface any tokenization failure to Ruby.
+    data.result = core_bpe
+        .encode(&data.text, &allowed_special)
+        .map(|(tokens, _last_piece_token_len)| tokens)
+        .map_err(|e| e.to_string());
     std::ptr::null_mut()
 }
 
@@ -99,7 +103,7 @@ impl CoreBPEWrapper {
             core_bpe: &self.core_bpe as *const _,
             text,
             allowed_special: HashSet::from_iter(allowed_special),
-            result: Vec::new(),
+            result: Ok(Vec::new()),
         };
 
         unsafe {
@@ -111,7 +115,9 @@ impl CoreBPEWrapper {
             );
         }
 
-        Ok(data.result)
+        data.result.map_err(|e| {
+            magnus::Error::new(magnus::Ruby::get().unwrap().exception_runtime_error(), e)
+        })
     }
 
     pub fn encode_with_special_tokens(&self, text: String) -> Vec<Rank> {