diff --git a/openwisp_monitoring/device/api/views.py b/openwisp_monitoring/device/api/views.py
index 5ca89e47e..732dc05bc 100644
--- a/openwisp_monitoring/device/api/views.py
+++ b/openwisp_monitoring/device/api/views.py
@@ -13,7 +13,7 @@
 from django.utils.translation import gettext_lazy as _
 from django_filters.rest_framework import DjangoFilterBackend
 from pytz import UTC
-from rest_framework import pagination, serializers, status
+from rest_framework import pagination, status
 from rest_framework.generics import (
     GenericAPIView,
     ListAPIView,
@@ -124,7 +124,7 @@ class DeviceMetricView(
         )
         .all()
     )
-    serializer_class = serializers.Serializer
+    serializer_class = MonitoringDeviceDetailSerializer
     permission_classes = [DevicePermission]
     schema = schema
 
@@ -155,7 +155,7 @@ def get(self, request, pk):
         response = super().get(request, pk)
         if not request.query_params.get("csv"):
             charts_data = dict(response.data)
-            device_metrics_data = MonitoringDeviceDetailSerializer(self.instance).data
+            device_metrics_data = self.serializer_class(self.instance).data
             return Response(
                 {**device_metrics_data, **charts_data}, status=status.HTTP_200_OK
             )
@@ -362,4 +362,4 @@ class WifiSessionDetailView(
     serializer_class = WifiSessionSerializer
 
 
-wifi_session_detail = WifiSessionDetailView.as_view()
+wifi_session_detail = WifiSessionDetailView.as_view()
\ No newline at end of file