diff --git a/src/persistence/memory.rs b/src/persistence/memory.rs
index b7edb131..58d81cfb 100644
--- a/src/persistence/memory.rs
+++ b/src/persistence/memory.rs
@@ -781,7 +781,7 @@ impl MemContractState {
     }
 }
 
-pub struct MemContract<M: Borrow<MemContractState>> {
+pub struct MemContract<M: Borrow<MemContractState> = MemContractState> {
     filter: HashMap<XWitnessId, WitnessOrd>,
     unfiltered: M,
 }
diff --git a/src/persistence/mod.rs b/src/persistence/mod.rs
index b20bc910..b2da2a38 100644
--- a/src/persistence/mod.rs
+++ b/src/persistence/mod.rs
@@ -43,8 +43,7 @@ pub use index::{
     Index, IndexError, IndexInconsistency, IndexProvider, IndexReadError, IndexReadProvider,
     IndexWriteError, IndexWriteProvider,
 };
-pub(crate) use memory::MemContract;
-pub use memory::{MemContractState, MemGlobalState, MemIndex, MemStash, MemState};
+pub use memory::{MemContract, MemContractState, MemGlobalState, MemIndex, MemStash, MemState};
 pub use stash::{
     ProviderError as StashProviderError, SchemaIfaces, Stash, StashDataError, StashError,
     StashInconsistency, StashProvider, StashReadProvider, StashWriteProvider,