diff --git a/selfprivacy_api/graphql/queries/monitoring.py b/selfprivacy_api/graphql/queries/monitoring.py
index adf5556..1ae2498 100644
--- a/selfprivacy_api/graphql/queries/monitoring.py
+++ b/selfprivacy_api/graphql/queries/monitoring.py
@@ -7,18 +7,27 @@ from selfprivacy_api.utils.prometheus import PrometheusQueries, PrometheusQueryR
 class Monitoring:
     @strawberry.field
     def disk_usage(
-        start: Optional[int] = None, end: Optional[int] = None, step: int = 60
+        self,
+        start: Optional[int] = None,
+        end: Optional[int] = None,
+        step: int = 60,
     ) -> PrometheusQueryResult:
         return PrometheusQueries.disk_usage(start, end, step)
 
     @strawberry.field
     def memory_usage(
-        start: Optional[int] = None, end: Optional[int] = None, step: int = 60
+        self,
+        start: Optional[int] = None,
+        end: Optional[int] = None,
+        step: int = 60,
     ) -> PrometheusQueryResult:
         return PrometheusQueries.memory_usage(start, end, step)
 
     @strawberry.field
     def cpu_usage(
-        start: Optional[int] = None, end: Optional[int] = None, step: int = 60
+        self,
+        start: Optional[int] = None,
+        end: Optional[int] = None,
+        step: int = 60,
     ) -> PrometheusQueryResult:
         return PrometheusQueries.cpu_usage(start, end, step)
diff --git a/selfprivacy_api/utils/prometheus.py b/selfprivacy_api/utils/prometheus.py
index a9935a2..23e7958 100644
--- a/selfprivacy_api/utils/prometheus.py
+++ b/selfprivacy_api/utils/prometheus.py
@@ -36,11 +36,11 @@ class PrometheusQueries:
             if response.status_code != 200:
                 raise Exception("Prometheus returned unexpected HTTP status code")
             json = response.json()
-            if json['status'] != 'success':
+            if json["status"] != "success":
                 raise Exception("Prometheus returned unexpected status")
-            result = json['data']
+            result = json["data"]
             return PrometheusQueryResult(
-                result_type=result['resultType'], result=result['result']
+                result_type=result["resultType"], result=result["result"]
             )
         except Exception as error:
             raise Exception("Prometheus request failed! " + str(error))