diff --git a/src/corebpe.rs b/src/corebpe.rs
index 07fff28..1bee6fc 100644
--- a/src/corebpe.rs
+++ b/src/corebpe.rs
@@ -166,7 +166,7 @@ const MAX_NUM_THREADS: usize = 8;
 
 #[derive(Debug)]
 pub struct CoreBPE {
-    encoder: Arc<HashMap<Vec<u8>, usize>>,
+    pub encoder: HashMap<Vec<u8>, usize>,
     special_tokens_encoder: HashMap<String, usize>,
     decoder: HashMap<usize, Vec<u8>>,
     special_tokens_decoder: HashMap<usize, Vec<u8>>,
@@ -429,7 +429,7 @@ impl CoreBPE {
 
 impl CoreBPE {
     pub fn new(
-        encoder: Arc<HashMap<Vec<u8>, usize>>,
+        encoder: HashMap<Vec<u8>, usize>,
         special_tokens_encoder: HashMap<String, usize>,
         pattern: &str,
     ) -> Result<Self, fancy_regex::Error> {
diff --git a/src/encoding.rs b/src/encoding.rs
index d77f6d7..7a9e0ca 100644
--- a/src/encoding.rs
+++ b/src/encoding.rs
@@ -13,8 +13,6 @@ pub struct Encoding {
     pub name: String,
     /// The regular expression pattern used to split text into pieces.
     pat_str: String,
-    /// The map from mergeable byte sequences to their ranks.
-    mergeable_ranks: Arc<HashMap<Vec<u8>, usize>>,
     /// The maximum length of the keys in `mergeable_ranks`.
     mergeable_ranks_max_key_len: usize,
     /// All prefixes of the mergeable ranks. May or may not be tokens themselves!
@@ -64,7 +62,7 @@ impl Encoding {
     pub fn new(
         name: &str,
         pat_str: &str,
-        mergeable_ranks: Arc<HashMap<Vec<u8>, usize>>,
+        mergeable_ranks: HashMap<Vec<u8>, usize>,
         special_tokens: HashMap<String, usize>,
         explicit_n_vocab: Option<usize>,
     ) -> Result<Self, EncodingError> {
@@ -113,7 +111,6 @@ impl Encoding {
         Ok(Self {
             name: name.to_string(),
             pat_str: pat_str.to_string(),
-            mergeable_ranks,
             mergeable_ranks_max_key_len,
             prefixes_of_mergeable_ranks,
             special_tokens,
@@ -157,7 +154,7 @@ impl Encoding {
                 if current_token.len() > 1 {
                     new_current_token.clear();
                     new_current_token.push(current_token.pop().unwrap());
-                    while !self.mergeable_ranks.contains_key(&current_token) {
+                    while !self.core_bpe.encoder.contains_key(&current_token) {
                         if current_token.len() == 1 {
                             break;
                         }
@@ -177,14 +174,14 @@ impl Encoding {
             }
         }
 
-        while !self.mergeable_ranks.contains_key(&current_token) {
+        while !self.core_bpe.encoder.contains_key(&current_token) {
             if current_token.len() == 0 {
                 break;
             }
             if current_token.len() > 1 {
                 new_current_token.clear();
                 new_current_token.push(current_token.pop().unwrap());
-                while !self.mergeable_ranks.contains_key(&current_token) {
+                while !self.core_bpe.encoder.contains_key(&current_token) {
                     if current_token.len() == 1 {
                         break;
                     }
diff --git a/src/load.rs b/src/load.rs
index 0b324d7..988ffe3 100644
--- a/src/load.rs
+++ b/src/load.rs
@@ -5,7 +5,6 @@ use sha2::Sha256;
 // call its methods without adding to the namespace.
 use base64::engine::general_purpose::STANDARD as BASE64;
 use base64::engine::Engine as _;
-use std::sync::Arc;
 
 // define the error
 #[derive(Debug, Clone)]
@@ -17,7 +16,7 @@ pub enum Error {
 pub fn load_tiktoken_bpe(
     tiktoken_bpe_contents: &[u8],
     shasum: &str,
-) -> Result<Arc<HashMap<Vec<u8>, usize>>, Error> {
+) -> Result<HashMap<Vec<u8>, usize>, Error> {
     // check the shasum
     let mut hasher = Sha256::new();
     hasher.update(tiktoken_bpe_contents);
@@ -43,5 +42,5 @@ pub fn load_tiktoken_bpe(
         map.insert(token, rank);
     }
     map.shrink_to_fit();
-    Ok(Arc::new(map))
+    Ok(map)
 }