diff --git a/src/cookies.ts b/src/cookies.ts
index bde02a4..54cac5a 100644
--- a/src/cookies.ts
+++ b/src/cookies.ts
@@ -342,7 +342,7 @@ export function createStorageFromOptions(
 
         let decoded = chunkedCookie;
 
-        if (chunkedCookie !== null && chunkedCookie.startsWith(BASE64_PREFIX)) {
+        if (typeof chunkedCookie === 'string' && chunkedCookie.startsWith(BASE64_PREFIX)) {
           decoded = stringFromBase64URL(
             chunkedCookie.substring(BASE64_PREFIX.length),
           );