diff --git a/daemawiki-service/src/main/java/org/daemawiki/domain/mail/usecase/service/UserMailSendService.java b/daemawiki-service/src/main/java/org/daemawiki/domain/mail/usecase/service/UserMailSendService.java
index 9617dd26..85d84799 100644
--- a/daemawiki-service/src/main/java/org/daemawiki/domain/mail/usecase/service/UserMailSendService.java
+++ b/daemawiki-service/src/main/java/org/daemawiki/domain/mail/usecase/service/UserMailSendService.java
@@ -103,9 +103,15 @@ private String getMailTemplate(String key) {
 
     private String getRandomCode() {
         SecureRandom secureRandom = new SecureRandom();
+        byte[] seed = new byte[32];
+        secureRandom.nextBytes(seed);
+        secureRandom.setSeed(seed);
         byte[] randomBytes = new byte[4];
         secureRandom.nextBytes(randomBytes);
-        return Base64.getUrlEncoder().withoutPadding().encodeToString(randomBytes);
+
+        return Base64.getUrlEncoder()
+                .withoutPadding()
+                .encodeToString(randomBytes);
     }
 
 }