diff --git a/public/scripts/openai.js b/public/scripts/openai.js
index 1dc07ba3c..d96e851e4 100644
--- a/public/scripts/openai.js
+++ b/public/scripts/openai.js
@@ -59,7 +59,7 @@ import {
     resetScrollHeight,
     stringFormat,
 } from "./utils.js";
-import { countTokensOpenAI } from "./tokenizers.js";
+import { countTokensOpenAI, getTokenizerModel } from "./tokenizers.js";
 import { formatInstructModeChat, formatInstructModeExamples, formatInstructModePrompt, formatInstructModeSystemPrompt } from "./instruct-mode.js";
 
 export {
@@ -1541,7 +1541,7 @@ async function calculateLogitBias() {
     let result = {};
 
     try {
-        const reply = await fetch(`/openai_bias?model=${oai_settings.openai_model}`, {
+        const reply = await fetch(`/openai_bias?model=${getTokenizerModel()}`, {
             method: 'POST',
             headers: getRequestHeaders(),
             body,
diff --git a/server.js b/server.js
index 0c908e55d..fe8407446 100644
--- a/server.js
+++ b/server.js
@@ -57,7 +57,7 @@ const statsHelpers = require('./statsHelpers.js');
 const { readSecret, migrateSecrets, SECRET_KEYS } = require('./src/secrets');
 const { delay, getVersion, deepMerge } = require('./src/util');
 const { invalidateThumbnail, ensureThumbnailCache } = require('./src/thumbnails');
-const { getTokenizerModel, getTiktokenTokenizer, loadTokenizers, TEXT_COMPLETION_MODELS } = require('./src/tokenizers');
+const { getTokenizerModel, getTiktokenTokenizer, loadTokenizers, TEXT_COMPLETION_MODELS, getSentencepiceTokenizer, sentencepieceTokenizers } = require('./src/tokenizers');
 const { convertClaudePrompt } = require('./src/chat-completion');
 
 // Work around a node v20.0.0, v20.1.0, and v20.2.0 bug. The issue was fixed in v20.3.0.
@@ -2762,57 +2762,71 @@ app.post("/openai_bias", jsonParser, async function (request, response) {
     if (!request.body || !Array.isArray(request.body))
         return response.sendStatus(400);
 
-    let result = {};
+    try {
+        const result = {};
+        const model = getTokenizerModel(String(request.query.model || ''));
 
-    const model = getTokenizerModel(String(request.query.model || ''));
-
-    // no bias for claude
-    if (model == 'claude') {
-        return response.send(result);
-    }
-
-    const tokenizer = getTiktokenTokenizer(model);
-
-    for (const entry of request.body) {
-        if (!entry || !entry.text) {
-            continue;
+        // no bias for claude
+        if (model == 'claude') {
+            return response.send(result);
         }
 
-        try {
-            const tokens = getEntryTokens(entry.text);
+        let encodeFunction;
 
-            for (const token of tokens) {
-                result[token] = entry.value;
+        if (sentencepieceTokenizers.includes(model)) {
+            const tokenizer = getSentencepiceTokenizer(model);
+            encodeFunction = (text) => new Uint32Array(tokenizer.encodeIds(text));
+        } else {
+            const tokenizer = getTiktokenTokenizer(model);
+            encodeFunction = (tokenizer.encode.bind(tokenizer));
+        }
+
+
+        for (const entry of request.body) {
+            if (!entry || !entry.text) {
+                continue;
             }
-        } catch {
-            console.warn('Tokenizer failed to encode:', entry.text);
-        }
-    }
 
-    // not needed for cached tokenizers
-    //tokenizer.free();
-    return response.send(result);
-
-    /**
-     * Gets tokenids for a given entry
-     * @param {string} text Entry text
-     * @returns {Uint32Array} Array of token ids
-     */
-    function getEntryTokens(text) {
-        // Get raw token ids from JSON array
-        if (text.trim().startsWith('[') && text.trim().endsWith(']')) {
             try {
-                const json = JSON.parse(text);
-                if (Array.isArray(json) && json.every(x => typeof x === 'number')) {
-                    return new Uint32Array(json);
+                const tokens = getEntryTokens(entry.text, encodeFunction);
+
+                for (const token of tokens) {
+                    result[token] = entry.value;
                 }
             } catch {
-                // ignore
+                console.warn('Tokenizer failed to encode:', entry.text);
             }
         }
 
-        // Otherwise, get token ids from tokenizer
-        return tokenizer.encode(text);
+        // not needed for cached tokenizers
+        //tokenizer.free();
+        return response.send(result);
+
+        /**
+         * Gets tokenids for a given entry
+         * @param {string} text Entry text
+         * @param {(string) => Uint32Array} encode Function to encode text to token ids
+         * @returns {Uint32Array} Array of token ids
+         */
+        function getEntryTokens(text, encode) {
+            // Get raw token ids from JSON array
+            if (text.trim().startsWith('[') && text.trim().endsWith(']')) {
+                try {
+                    const json = JSON.parse(text);
+                    if (Array.isArray(json) && json.every(x => typeof x === 'number')) {
+                        return new Uint32Array(json);
+                    }
+                } catch {
+                    // ignore
+                }
+            }
+
+            // Otherwise, get token ids from tokenizer
+            return encode(text);
+        }
+    } catch (error) {
+        console.error(error);
+        return response.send({});
     }
 });
 
diff --git a/src/tokenizers.js b/src/tokenizers.js
index 264e0706d..771da69fe 100644
--- a/src/tokenizers.js
+++ b/src/tokenizers.js
@@ -60,6 +60,36 @@ async function loadSentencepieceTokenizer(modelPath) {
     }
 };
 
+const sentencepieceTokenizers = [
+    'llama',
+    'nerdstash',
+    'nerdstash_v2',
+    'mistral',
+];
+
+/**
+ * Gets the Sentencepiece tokenizer by the model name.
+ * @param {string} model Sentencepiece model name
+ * @returns {*} Sentencepiece tokenizer
+ */
+function getSentencepiceTokenizer(model) {
+    if (model.includes('llama')) {
+        return spp_llama;
+    }
+
+    if (model.includes('nerdstash')) {
+        return spp_nerd;
+    }
+
+    if (model.includes('mistral')) {
+        return spp_mistral;
+    }
+
+    if (model.includes('nerdstash_v2')) {
+        return spp_nerd_v2;
+    }
+}
+
 async function countSentencepieceTokens(spp, text) {
     // Fallback to strlen estimation
     if (!spp) {
@@ -438,5 +468,7 @@ module.exports = {
     countClaudeTokens,
     loadTokenizers,
     registerEndpoints,
+    getSentencepiceTokenizer,
+    sentencepieceTokenizers,
 }