diff --git a/actors/miner/src/types.rs b/actors/miner/src/types.rs
index 77d59b953..8ccf046d9 100644
--- a/actors/miner/src/types.rs
+++ b/actors/miner/src/types.rs
@@ -510,6 +510,7 @@ pub struct SectorUpdateManifest {
 }
 
 #[derive(Clone, Debug, Eq, PartialEq, Serialize_tuple, Deserialize_tuple)]
+#[serde(transparent)]
 pub struct ProveReplicaUpdates2Return {
     pub activation_results: BatchReturn,
 }