diff --git a/vite-frontend/src/pages/tunnel/form.ts b/vite-frontend/src/pages/tunnel/form.ts
index e6b636c..334527d 100644
--- a/vite-frontend/src/pages/tunnel/form.ts
+++ b/vite-frontend/src/pages/tunnel/form.ts
@@ -26,6 +26,9 @@ const isValidProbeIPv4 = (host: string) => {
       if (!/^\d+$/.test(part)) {
         return false;
       }
+      if (part.length > 1 && part.startsWith("0")) {
+        return false;
+      }
 
       const value = Number(part);