diff --git a/watcher/api/controllers/v1/audit_template.py b/watcher/api/controllers/v1/audit_template.py
index 4f673c61e..888e239a5 100644
--- a/watcher/api/controllers/v1/audit_template.py
+++ b/watcher/api/controllers/v1/audit_template.py
@@ -448,7 +448,7 @@ class AuditTemplatesController(rest.RestController):
                                         sort_key, sort_dir, expand=False,
                                         resource_url=None):
         api_utils.validate_search_filters(
-            filters, list(objects.audit_template.AuditTemplate.fields.keys()) +
+            filters, list(objects.audit_template.AuditTemplate.fields) +
             ["goal_uuid", "goal_name", "strategy_uuid", "strategy_name"])
         limit = api_utils.validate_limit(limit)
         api_utils.validate_sort_dir(sort_dir)
diff --git a/watcher/api/controllers/v1/goal.py b/watcher/api/controllers/v1/goal.py
index a7dd28b16..43ba33d29 100644
--- a/watcher/api/controllers/v1/goal.py
+++ b/watcher/api/controllers/v1/goal.py
@@ -170,7 +170,7 @@ class GoalsController(rest.RestController):
         limit = api_utils.validate_limit(limit)
         api_utils.validate_sort_dir(sort_dir)
 
-        sort_db_key = (sort_key if sort_key in objects.Goal.fields.keys()
+        sort_db_key = (sort_key if sort_key in objects.Goal.fields
                        else None)
 
         marker_obj = None
diff --git a/watcher/api/controllers/v1/service.py b/watcher/api/controllers/v1/service.py
index 63ea1794a..e7f77c93f 100644
--- a/watcher/api/controllers/v1/service.py
+++ b/watcher/api/controllers/v1/service.py
@@ -104,7 +104,7 @@ class Service(base.APIBase):
     def __init__(self, **kwargs):
         super(Service, self).__init__()
 
-        fields = list(objects.Service.fields.keys()) + ['status']
+        fields = list(objects.Service.fields) + ['status']
         self.fields = []
         for field in fields:
             self.fields.append(field)
@@ -194,7 +194,7 @@ class ServicesController(rest.RestController):
         limit = api_utils.validate_limit(limit)
         api_utils.validate_sort_dir(sort_dir)
 
-        sort_db_key = (sort_key if sort_key in objects.Service.fields.keys()
+        sort_db_key = (sort_key if sort_key in objects.Service.fields
                        else None)
 
         marker_obj = None
diff --git a/watcher/api/controllers/v1/strategy.py b/watcher/api/controllers/v1/strategy.py
index 2c74da14a..dc7e2c5f9 100644
--- a/watcher/api/controllers/v1/strategy.py
+++ b/watcher/api/controllers/v1/strategy.py
@@ -210,12 +210,12 @@ class StrategiesController(rest.RestController):
     def _get_strategies_collection(self, filters, marker, limit, sort_key,
                                    sort_dir, expand=False, resource_url=None):
         api_utils.validate_search_filters(
-            filters, list(objects.strategy.Strategy.fields.keys()) +
+            filters, list(objects.strategy.Strategy.fields) +
             ["goal_uuid", "goal_name"])
         limit = api_utils.validate_limit(limit)
         api_utils.validate_sort_dir(sort_dir)
 
-        sort_db_key = (sort_key if sort_key in objects.Strategy.fields.keys()
+        sort_db_key = (sort_key if sort_key in objects.Strategy.fields
                        else None)
 
         marker_obj = None
diff --git a/watcher/api/controllers/v1/utils.py b/watcher/api/controllers/v1/utils.py
index 2ad5b49bf..60d503829 100644
--- a/watcher/api/controllers/v1/utils.py
+++ b/watcher/api/controllers/v1/utils.py
@@ -57,7 +57,7 @@ def validate_sort_dir(sort_dir):
 def validate_search_filters(filters, allowed_fields):
     # Very lightweight validation for now
     # todo: improve this (e.g. https://www.parse.com/docs/rest/guide/#queries)
-    for filter_name in filters.keys():
+    for filter_name in filters:
         if filter_name not in allowed_fields:
             raise wsme.exc.ClientSideError(
                 _("Invalid filter: %s") % filter_name)
diff --git a/watcher/api/scheduling.py b/watcher/api/scheduling.py
index 4a2b0538d..9a3a42385 100644
--- a/watcher/api/scheduling.py
+++ b/watcher/api/scheduling.py
@@ -42,7 +42,7 @@ class APISchedulingService(scheduling.BackgroundSchedulerService):
         services = objects.service.Service.list(context)
         for service in services:
             result = self.get_service_status(context, service.id)
-            if service.id not in self.services_status.keys():
+            if service.id not in self.services_status:
                 self.services_status[service.id] = result
                 continue
             if self.services_status[service.id] != result: