diff --git a/src/prompt-converters.js b/src/prompt-converters.js
index 38a6854a9..a7e783a34 100644
--- a/src/prompt-converters.js
+++ b/src/prompt-converters.js
@@ -545,7 +545,7 @@ function convertMistralMessages(messages, charName = '', userName = '') {
         lastMsg.prefix = true;
     }
 
-    const sanitizeToolId = (id) => crypto.hash('sha512', id, 'base64').slice(0, 9);
+    const sanitizeToolId = (id) => crypto.hash('sha512', id, 'hex').slice(0, 9);
 
     // Doesn't support completion names, so prepend if not already done by the frontend (e.g. for group chats).
     messages.forEach(msg => {