diff --git a/client/src/utils/postalcode.ts b/client/src/utils/postalcode.ts
index 93177698..59fdac69 100644
--- a/client/src/utils/postalcode.ts
+++ b/client/src/utils/postalcode.ts
@@ -1,7 +1,10 @@
 export function validatePostalCode(input: string) {
+  // Remove non-ASCII characters
+  // eslint-disable-next-line no-control-regex
+  input = input.replace(/[^\x00-\x7F]/g, "");
   if (input.length < 4) {
     return false;
   }
-  const regex = /^\d+$/;
+  const regex = /^[0-9]+$/;
   return regex.test(input);
 }