diff --git a/modoboa/admin/serializers.py b/modoboa/admin/serializers.py
index 009b475d6..ccddf4e58 100644
--- a/modoboa/admin/serializers.py
+++ b/modoboa/admin/serializers.py
@@ -26,7 +26,6 @@ from . import lib, models
 
 
 class DomainSerializer(serializers.ModelSerializer):
-
     """Base Domain serializer."""
 
     class Meta:
@@ -34,9 +33,12 @@ class DomainSerializer(serializers.ModelSerializer):
         fields = (
             "pk", "name", "quota", "default_mailbox_quota", "enabled", "type",
             "enable_dkim", "dkim_key_selector", "dkim_key_length",
-            "dkim_public_key", "dkim_private_key_path"
+            "dkim_public_key", "dkim_private_key_path",
+            "mailbox_count", "mbalias_count", "domainalias_count"
+        )
+        read_only_fields = (
+            "pk", "mailbox_count", "mbalias_count", "domainalias_count"
         )
-        read_only_fields = ("pk", )
 
     def validate_name(self, value):
         """Check name constraints."""
diff --git a/modoboa/admin/tests/test_api.py b/modoboa/admin/tests/test_api.py
index d57b657bb..51d82b6c0 100644
--- a/modoboa/admin/tests/test_api.py
+++ b/modoboa/admin/tests/test_api.py
@@ -49,8 +49,10 @@ class DomainAPITestCase(ModoAPITestCase):
         url = reverse(
             "api:domain-detail", args=[domain["pk"]])
         response = self.client.get(url)
+        data = response.json()
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.data["name"], domain["name"])
+        self.assertEqual(data["name"], domain["name"])
+        self.assertEqual(data["mailbox_count"], 2)
 
     def test_create_domain(self):
         """Check domain creation."""