diff --git a/src/utils/mrz.ts b/src/utils/mrz.ts
index 8de24031..7428eea6 100644
--- a/src/utils/mrz.ts
+++ b/src/utils/mrz.ts
@@ -140,7 +140,11 @@ function mrzCleanResult(obj: Record<string, string>) {
 }
 
 export function checkSum(data: string) {
+  if (!/[0-9A-Z<]/.test(data)) return null;
+
   const sum = data.split('').reduce((a, v, i) => {
+    if (v === '<') return a;
+
     const num = Number(v);
     const weight = [7, 3, 1][i % 3];