diff --git a/check_home_assistant_state.py b/check_home_assistant_state.py
index 259cfd4..11a69dc 100755
--- a/check_home_assistant_state.py
+++ b/check_home_assistant_state.py
@@ -148,7 +148,11 @@ class Entities(nagiosplugin.Resource):
         )
 
     def probe(self):
-        template_filter = f"states|selectattr('attributes.device_class', 'eq', '{ self.device_class }')"
+        template_filter = "states"
+        if self.device_class:
+            template_filter += (
+                f"|selectattr('attributes.device_class', 'eq', '{ self.device_class }')"
+            )
         for f in self.filters:
             op = "ne" if f.negated else "eq"
             template_filter += (
@@ -351,7 +355,7 @@ def main():
         "-d",
         "--device-class",
         type=str,
-        required=True,
+        required=False,
         help="device class of entities to monitor",
     )
     common_args.add_argument(
@@ -469,7 +473,7 @@ def main():
                 max=args.max,
                 **parsed_common_args,
             ),
-            ScalarOrUnknownContext(args.device_class, args.warning, args.critical),
+            ScalarOrUnknownContext("scalar_entities", args.warning, args.critical),
         )
     elif args.subparser_name == "text":
         check = nagiosplugin.Check(
@@ -479,7 +483,7 @@ def main():
                 numeric=False,
                 **parsed_common_args,
             ),
-            RegexContext(args.device_class, args.ok, args.warning, args.critical),
+            RegexContext("text_entities", args.ok, args.warning, args.critical),
         )
 
     check.main(args.verbose)