diff --git a/substrate/demo/primitives/src/transaction.rs b/substrate/demo/primitives/src/transaction.rs
index e75b67d745754faf0ec0179e711aec98ec1ab982..ae8dd0bd551e8fa915eaefa92ac27a44a4bae908 100644
--- a/substrate/demo/primitives/src/transaction.rs
+++ b/substrate/demo/primitives/src/transaction.rs
@@ -294,7 +294,7 @@ impl Slicable for Function {
 				to.using_encoded(|s| v.extend(s));
 				amount.using_encoded(|s| v.extend(s));
 			}
-			_ => {}
+			_ => { unimplemented!() }
 		}
 
 		v