diff --git a/src/runtime/browser/base64url.ts b/src/runtime/browser/base64url.ts
index 8192a180..fe4263fc 100644
--- a/src/runtime/browser/base64url.ts
+++ b/src/runtime/browser/base64url.ts
@@ -6,7 +6,13 @@ export const encode = (input: Uint8Array | string) => {
   if (typeof unencoded === 'string') {
     unencoded = encoder.encode(unencoded)
   }
-  const base64string = globalThis.btoa(String.fromCharCode.apply(0, [...unencoded]))
+  const CHUNK_SIZE = 0x8000
+  const arr = []
+  for (let i = 0; i < unencoded.length; i += CHUNK_SIZE) {
+    // @ts-expect-error
+    arr.push(String.fromCharCode.apply(null, unencoded.subarray(i, i + CHUNK_SIZE)))
+  }
+  const base64string = globalThis.btoa(arr.join(''))
   return base64string.replace(/=/g, '').replace(/\+/g, '-').replace(/\//g, '_')
 }