diff --git a/test/server/Test.interface.yaml b/test/server/Test.interface.yaml
index 7daea7d..2f86d70 100644
--- a/test/server/Test.interface.yaml
+++ b/test/server/Test.interface.yaml
@@ -12,3 +12,5 @@
       type: int64
       flags:
           - const
+    - name: Countable
+      type: size