diff --git a/rflx/session.py b/rflx/session.py
index 0007b2a50..2520f3ed6 100644
--- a/rflx/session.py
+++ b/rflx/session.py
@@ -181,8 +181,8 @@ def __validate_state_reachability(self) -> None:
                 self.location,
             )
 
-    @classmethod
-    def __entity_name(cls, decl: Declaration) -> str:
+    @staticmethod
+    def __entity_name(decl: Declaration) -> str:
         if isinstance(decl, SubprogramDeclaration):
             return "subprogram"
         if isinstance(decl, VariableDeclaration):
@@ -193,7 +193,7 @@ def __entity_name(cls, decl: Declaration) -> str:
             return "channel"
         if isinstance(decl, PrivateDeclaration):
             return "private"
-        assert False, f"Unsupported entity {type(decl).__name__}"
+        assert False, f"unsupported entity {type(decl).__name__}"
 
     def __validate_declarations(self) -> None:
         for s in self.states: