diff --git a/src/lib/validation.ts b/src/lib/validation.ts
index f8aa168..635b30a 100644
--- a/src/lib/validation.ts
+++ b/src/lib/validation.ts
@@ -97,7 +97,7 @@ export const IsValidDateStr = (s: string): boolean => {
     for (let i = 0; i < 10; i++) {
         if (i === 4 || i === 7) continue;
         const c = s.charCodeAt(i);
-        if (!isDigit(i)) return false;
+        if (!isDigit(c)) return false;
     }
 
     const y = parseInt(s.substring(0, 4), 10);