diff --git a/tempest/api_schema/response/compute/availability_zone.py b/tempest/api_schema/response/compute/availability_zone.py
index c1abc64..ab3e2ea 100644
--- a/tempest/api_schema/response/compute/availability_zone.py
+++ b/tempest/api_schema/response/compute/availability_zone.py
@@ -27,7 +27,7 @@
                     'properties': {
                         'available': {'type': 'boolean'},
                         'active': {'type': 'boolean'},
-                        'updated_at': {'type': 'string'}
+                        'updated_at': {'type': ['string', 'null']}
                     },
                     'required': ['available', 'active', 'updated_at']
                 }
diff --git a/tempest/api_schema/response/compute/services.py b/tempest/api_schema/response/compute/services.py
index eaba129..fc42b89 100644
--- a/tempest/api_schema/response/compute/services.py
+++ b/tempest/api_schema/response/compute/services.py
@@ -28,7 +28,7 @@
                         'state': {'type': 'string'},
                         'binary': {'type': 'string'},
                         'status': {'type': 'string'},
-                        'updated_at': {'type': 'string'},
+                        'updated_at': {'type': ['string', 'null']},
                         'disabled_reason': {'type': ['string', 'null']}
                     },
                     'required': ['id', 'zone', 'host', 'state', 'binary',