diff --git a/backend/src/main/java/com/twtw/backend/domain/deadletter/DeadLetterConsumer.java b/backend/src/main/java/com/twtw/backend/domain/deadletter/DeadLetterConsumer.java
index a59f787..8e94df9 100644
--- a/backend/src/main/java/com/twtw/backend/domain/deadletter/DeadLetterConsumer.java
+++ b/backend/src/main/java/com/twtw/backend/domain/deadletter/DeadLetterConsumer.java
@@ -15,11 +15,13 @@
 @Component
 public class DeadLetterConsumer {
 
+    private static final String ALERT_URL = "https://hooks.slack.com/services/";
+    private static final String ALERT_MESSAGE = "{\"text\": \"Dead letter received: %s\"}";
     private final WebClient webClient;
     private final String slackUrl;
 
     public DeadLetterConsumer(@Value("${slack.url}") final String slackUrl) {
-        this.webClient = WebClient.create("https://hooks.slack.com/services/");
+        this.webClient = WebClient.create(ALERT_URL);
         this.slackUrl = slackUrl;
     }
 
@@ -29,7 +31,7 @@ public void handleDeadLetterMessage(final NotificationRequest message) {
         webClient
                 .post()
                 .uri(slackUrl)
-                .bodyValue("{\"text\": \"Dead letter received: " + message + "\"}")
+                .bodyValue(String.format(ALERT_MESSAGE, message))
                 .retrieve()
                 .onStatus(HttpStatusCode::isError, ClientResponse::createException);
     }
diff --git a/backend/src/main/java/com/twtw/backend/domain/notification/messagequeue/FcmConsumer.java b/backend/src/main/java/com/twtw/backend/domain/notification/messagequeue/FcmConsumer.java
index fdbf711..21cb1f9 100644
--- a/backend/src/main/java/com/twtw/backend/domain/notification/messagequeue/FcmConsumer.java
+++ b/backend/src/main/java/com/twtw/backend/domain/notification/messagequeue/FcmConsumer.java
@@ -2,35 +2,45 @@
 
 import com.google.firebase.messaging.FirebaseMessaging;
 import com.google.firebase.messaging.FirebaseMessagingException;
+import com.rabbitmq.client.Channel;
 import com.twtw.backend.domain.notification.dto.NotificationRequest;
 import com.twtw.backend.domain.notification.entity.Notification;
 import com.twtw.backend.domain.notification.repository.NotificationRepository;
 
+import lombok.RequiredArgsConstructor;
+
 import org.springframework.amqp.rabbit.annotation.RabbitListener;
+import org.springframework.amqp.support.AmqpHeaders;
+import org.springframework.messaging.handler.annotation.Header;
 import org.springframework.stereotype.Component;
 import org.springframework.transaction.annotation.Transactional;
 
+import java.io.IOException;
+import java.util.Optional;
 import java.util.UUID;
 
 @Component
+@RequiredArgsConstructor
 public class FcmConsumer {
     private final FirebaseMessaging firebaseMessaging;
     private final NotificationRepository notificationRepository;
 
-    public FcmConsumer(
-            FirebaseMessaging firebaseMessaging, NotificationRepository notificationRepository) {
-        this.firebaseMessaging = firebaseMessaging;
-        this.notificationRepository = notificationRepository;
-    }
-
     @Transactional
     @RabbitListener(queues = "notification.queue")
-    public void sendNotification(final NotificationRequest request)
-            throws FirebaseMessagingException {
+    public void sendNotification(
+            final NotificationRequest request,
+            final Channel channel,
+            @Header(AmqpHeaders.DELIVERY_TAG) final long tag)
+            throws FirebaseMessagingException, IOException {
         firebaseMessaging.send(request.toMessage());
 
-        notificationRepository
-                .findById(UUID.fromString(request.getNotificationId()))
-                .ifPresent(Notification::complete);
+        final Optional<Notification> notification =
+                notificationRepository.findById(UUID.fromString(request.getNotificationId()));
+
+        if (notification.isPresent()) {
+            notification.get().complete();
+            return;
+        }
+        channel.basicNack(tag, false, false);
     }
 }