diff --git a/example/net/poettering/Calculator.errors.yaml b/example/net/poettering/Calculator.errors.yaml
index 730e2a3..b2f6ee3 100644
--- a/example/net/poettering/Calculator.errors.yaml
+++ b/example/net/poettering/Calculator.errors.yaml
@@ -1,3 +1,6 @@
 - name: DivisionByZero
   description: >
     An attempt to divide by zero was attempted.
+- name: PermissionDenied
+  description: >
+    The user does not have enough privileges to perform the operation.
diff --git a/example/net/poettering/Calculator.interface.yaml b/example/net/poettering/Calculator.interface.yaml
index d289c21..af4dd1b 100644
--- a/example/net/poettering/Calculator.interface.yaml
+++ b/example/net/poettering/Calculator.interface.yaml
@@ -55,6 +55,12 @@
       default: Success
       description: >
         The current state of the Calculator.
+    - name: Owner
+      type: string
+      description: >
+        The name of the owner of the Calculator.
+      errors:
+        - self.Error.PermissionDenied
 signals:
     - name: Cleared
       description: >