diff --git a/nomad/app/dcat/common.py b/nomad/app/dcat/common.py
index 3b5f4c6913eca76d9f06155f21db7f1a39888cdf..131dbad6b6645ff075af9aee428f6da3880b964b 100644
--- a/nomad/app/dcat/common.py
+++ b/nomad/app/dcat/common.py
@@ -40,11 +40,11 @@ def url(*args, **kwargs):
 
 
 class Formats(str, Enum):
-    xml = ('xml',)
-    n3 = ('n3',)
-    turtle = ('turtle',)
-    nt = ('nt',)
-    pretty_xml = ('pretty-xml',)
+    xml = 'xml'
+    n3 = 'n3'
+    turtle = 'turtle'
+    nt = 'nt'
+    pretty_xml = 'pretty-xml'
     trig = 'trig'
 
 
diff --git a/nomad/app/v1/routers/north.py b/nomad/app/v1/routers/north.py
index dbae28e30079690dacbc95c7c5f50ef93c0b0323..63ece466b3297bff41dc51a3c7480b24b4040d4a 100644
--- a/nomad/app/v1/routers/north.py
+++ b/nomad/app/v1/routers/north.py
@@ -45,9 +45,9 @@ logger = get_logger(__name__)
 
 
 class ToolStateEnum(str, Enum):
-    running = ('running',)
-    starting = ('starting',)
-    stopping = ('stopping',)
+    running = 'running'
+    starting = 'starting'
+    stopping = 'stopping'
     stopped = 'stopped'