diff --git a/src/azul/chalice.py b/src/azul/chalice.py
index 781686d0a..f50089514 100644
--- a/src/azul/chalice.py
+++ b/src/azul/chalice.py
@@ -579,7 +579,7 @@ def bind(self, app: Chalice, handler_name: str | None = None) -> Self:
 
         @property
         def tf_function_resource_name(self) -> str:
-            assert self.handler_name is not None, 'Unbound decorator'
+            assert self.app_name is not None, 'Unbound decorator'
             if self.handler_name is None:
                 return self.app_name
             else: