diff --git a/tiktoken-rs/src/api.rs b/tiktoken-rs/src/api.rs
index 27cc7e4..c39b6a3 100644
--- a/tiktoken-rs/src/api.rs
+++ b/tiktoken-rs/src/api.rs
@@ -1,9 +1,14 @@
+use std::sync::Arc;
+
 use anyhow::{anyhow, Result};
+use lazy_static::lazy_static;
+use parking_lot::Mutex;
 
 use crate::{
     cl100k_base,
     model::get_context_size,
     o200k_base, p50k_base, p50k_edit, r50k_base,
+    singleton::*,
     tokenizer::{get_tokenizer, Tokenizer},
     CoreBPE,
 };
@@ -41,7 +46,8 @@ use crate::{
 /// based on the given model and prompt.
 pub fn get_completion_max_tokens(model: &str, prompt: &str) -> Result<usize> {
     let context_size = get_context_size(model);
-    let bpe = get_bpe_from_model(model)?;
+    let bpe_mutex = get_bpe_from_model(model)?;
+    let bpe = bpe_mutex.lock();
     let prompt_tokens = bpe.encode_with_special_tokens(prompt).len();
     Ok(context_size.saturating_sub(prompt_tokens))
 }
@@ -102,7 +108,8 @@ pub fn num_tokens_from_messages(
     if tokenizer != Tokenizer::Cl100kBase && tokenizer != Tokenizer::O200kBase {
         anyhow::bail!("Chat completion is only supported chat models")
     }
-    let bpe = get_bpe_from_tokenizer(tokenizer)?;
+    let bpe_mutex = get_bpe_from_tokenizer(tokenizer)?;
+    let bpe = bpe_mutex.lock();
 
     let (tokens_per_message, tokens_per_name) = if model.starts_with("gpt-3.5") {
         (
@@ -220,7 +227,7 @@ pub fn get_chat_completion_max_tokens(
 /// # Returns
 ///
 /// If successful, the function returns a `Result` containing the `CoreBPE` instance corresponding to the tokenizer used by the given model.
-pub fn get_bpe_from_model(model: &str) -> Result<CoreBPE> {
+pub fn get_bpe_from_model(model: &str) -> Result<Arc<Mutex<CoreBPE>>> {
     let tokenizer =
         get_tokenizer(model).ok_or_else(|| anyhow!("No tokenizer found for model {}", model))?;
     let bpe = get_bpe_from_tokenizer(tokenizer)?;
@@ -253,15 +260,16 @@ pub fn get_bpe_from_model(model: &str) -> Result<CoreBPE> {
 /// # Returns
 ///
 /// If successful, the function returns a `Result` containing the `CoreBPE` instance corresponding to the given tokenizer.
-pub fn get_bpe_from_tokenizer(tokenizer: Tokenizer) -> Result<CoreBPE> {
-    match tokenizer {
-        Tokenizer::O200kBase => o200k_base(),
-        Tokenizer::Cl100kBase => cl100k_base(),
-        Tokenizer::R50kBase => r50k_base(),
-        Tokenizer::P50kBase => p50k_base(),
-        Tokenizer::P50kEdit => p50k_edit(),
-        Tokenizer::Gpt2 => r50k_base(),
-    }
+pub fn get_bpe_from_tokenizer(tokenizer: Tokenizer) -> Result<Arc<Mutex<CoreBPE>>> {
+    let tok = match tokenizer {
+        Tokenizer::O200kBase => o200k_base_singleton(),
+        Tokenizer::Cl100kBase => cl100k_base_singleton(),
+        Tokenizer::R50kBase => r50k_base_singleton(),
+        Tokenizer::P50kBase => p50k_base_singleton(),
+        Tokenizer::P50kEdit => p50k_edit_singleton(),
+        Tokenizer::Gpt2 => r50k_base_singleton(),
+    };
+    Ok(tok)
 }
 
 #[cfg(test)]