diff --git a/codex/contracts/market.nim b/codex/contracts/market.nim
index e2065769..6357ee73 100644
--- a/codex/contracts/market.nim
+++ b/codex/contracts/market.nim
@@ -247,11 +247,14 @@ method canProofBeMarkedAsMissing*(
     trace "Proof cannot be marked as missing", msg = e.msg
     return false
 
-method reserveSlot*(id: SlotId): Future[bool] {.async.} =
+method reserveSlot*(market: OnChainMarket, id: SlotId) {.async.} =
   discard await market.contract.reserveSlot(id).confirm(0)
 
-method canReserveSlot*(id: SlotId): Future[bool] {.async.} =
-  discard await market.contract.canReserveSlot(id).confirm(0)
+method canReserveSlot*(
+  market: OnChainMarket,
+  id: SlotId): Future[bool] {.async.} =
+
+  await market.contract.canReserveSlot(id)
 
 method subscribeRequests*(market: OnChainMarket,
                          callback: OnRequest):
diff --git a/codex/contracts/marketplace.nim b/codex/contracts/marketplace.nim
index 6596c993..0c8b8b31 100644
--- a/codex/contracts/marketplace.nim
+++ b/codex/contracts/marketplace.nim
@@ -52,5 +52,5 @@ proc getPointer*(marketplace: Marketplace, id: SlotId): uint8 {.contract, view.}
 proc submitProof*(marketplace: Marketplace, id: SlotId, proof: Groth16Proof): ?TransactionResponse {.contract.}
 proc markProofAsMissing*(marketplace: Marketplace, id: SlotId, period: UInt256): ?TransactionResponse {.contract.}
 
-proc reserveSlot*(marketplace: Marketplace, id: SlotId): bool {.contract.}
+proc reserveSlot*(marketplace: Marketplace, id: SlotId): ?TransactionResponse {.contract.}
 proc canReserveSlot*(marketplace: Marketplace, id: SlotId): bool {.contract, view.}
diff --git a/codex/market.nim b/codex/market.nim
index 1ebe237d..94bf9c5a 100644
--- a/codex/market.nim
+++ b/codex/market.nim
@@ -161,10 +161,16 @@ method canProofBeMarkedAsMissing*(market: Market,
                                   period: Period): Future[bool] {.base, async.} =
   raiseAssert("not implemented")
 
-method reserveSlot*(id: SlotId): Future[bool] {.base, async.} =
+method reserveSlot*(
+  market: Market,
+  id: SlotId) {.base, async.} =
+
   raiseAssert("not implemented")
 
-method canReserveSlot*(id: SlotId): Future[bool] {.base, async.} =
+method canReserveSlot*(
+  market: Market,
+  id: SlotId): Future[bool] {.base, async.} =
+
   raiseAssert("not implemented")
 
 method subscribeFulfillment*(market: Market,
diff --git a/vendor/codex-contracts-eth b/vendor/codex-contracts-eth
index b62c72b5..d2ba8693 160000
--- a/vendor/codex-contracts-eth
+++ b/vendor/codex-contracts-eth
@@ -1 +1 @@
-Subproject commit b62c72b5e1a348c2d47c9f3c31c1d712e37286b7
+Subproject commit d2ba8693e772b83e80746ffadc1efc36c836caf0