diff --git a/src/v/rpc/service.h b/src/v/rpc/service.h
index e1d4abd615cd..59c8a5c8d748 100644
--- a/src/v/rpc/service.h
+++ b/src/v/rpc/service.h
@@ -92,9 +92,12 @@ struct service::execution_helper {
*/
vassert(
effective_version == version,
- "Unexpected encoding at effective {} != {}",
+ "Unexpected encoding at effective {} != {}. Input "
+ "{} Output {}",
effective_version,
- version);
+ version,
+ serde::type_str(),
+ serde::type_str