diff --git a/codex/contracts/market.nim b/codex/contracts/market.nim
index 6dd7e2b3..69383065 100644
--- a/codex/contracts/market.nim
+++ b/codex/contracts/market.nim
@@ -176,7 +176,7 @@ method fillSlot(market: OnChainMarket,
 
 method freeSlot*(market: OnChainMarket, slotId: SlotId) {.async.} =
   convertEthersError:
-    var freeSlot: Future[?TransactionResponse]
+    var freeSlot: Future[Confirmable]
     if rewardRecipient =? market.rewardRecipient:
       # If --reward-recipient specified, use it as the reward recipient, and use
       # the SP's address as the collateral recipient
diff --git a/codex/contracts/marketplace.nim b/codex/contracts/marketplace.nim
index 6425bfa0..f3bac79d 100644
--- a/codex/contracts/marketplace.nim
+++ b/codex/contracts/marketplace.nim
@@ -23,12 +23,12 @@ proc slashMisses*(marketplace: Marketplace): UInt256 {.contract, view.}
 proc slashPercentage*(marketplace: Marketplace): UInt256 {.contract, view.}
 proc minCollateralThreshold*(marketplace: Marketplace): UInt256 {.contract, view.}
 
-proc requestStorage*(marketplace: Marketplace, request: StorageRequest): ?TransactionResponse {.contract.}
-proc fillSlot*(marketplace: Marketplace, requestId: RequestId, slotIndex: UInt256, proof: Groth16Proof): ?TransactionResponse {.contract.}
-proc withdrawFunds*(marketplace: Marketplace, requestId: RequestId): ?TransactionResponse {.contract.}
-proc withdrawFunds*(marketplace: Marketplace, requestId: RequestId, withdrawAddress: Address): ?TransactionResponse {.contract.}
-proc freeSlot*(marketplace: Marketplace, id: SlotId): ?TransactionResponse {.contract.}
-proc freeSlot*(marketplace: Marketplace, id: SlotId, rewardRecipient: Address, collateralRecipient: Address): ?TransactionResponse {.contract.}
+proc requestStorage*(marketplace: Marketplace, request: StorageRequest): Confirmable {.contract.}
+proc fillSlot*(marketplace: Marketplace, requestId: RequestId, slotIndex: UInt256, proof: Groth16Proof): Confirmable {.contract.}
+proc withdrawFunds*(marketplace: Marketplace, requestId: RequestId): Confirmable {.contract.}
+proc withdrawFunds*(marketplace: Marketplace, requestId: RequestId, withdrawAddress: Address): Confirmable {.contract.}
+proc freeSlot*(marketplace: Marketplace, id: SlotId): Confirmable {.contract.}
+proc freeSlot*(marketplace: Marketplace, id: SlotId, rewardRecipient: Address, collateralRecipient: Address): Confirmable {.contract.}
 proc getRequest*(marketplace: Marketplace, id: RequestId): StorageRequest {.contract, view.}
 proc getHost*(marketplace: Marketplace, id: SlotId): Address {.contract, view.}
 proc getActiveSlot*(marketplace: Marketplace, id: SlotId): Slot {.contract, view.}
@@ -49,8 +49,8 @@ proc willProofBeRequired*(marketplace: Marketplace, id: SlotId): bool {.contract
 proc getChallenge*(marketplace: Marketplace, id: SlotId): array[32, byte] {.contract, view.}
 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 submitProof*(marketplace: Marketplace, id: SlotId, proof: Groth16Proof): Confirmable {.contract.}
+proc markProofAsMissing*(marketplace: Marketplace, id: SlotId, period: UInt256): Confirmable {.contract.}
 
-proc reserveSlot*(marketplace: Marketplace, requestId: RequestId, slotIndex: UInt256): ?TransactionResponse {.contract.}
+proc reserveSlot*(marketplace: Marketplace, requestId: RequestId, slotIndex: UInt256): Confirmable {.contract.}
 proc canReserveSlot*(marketplace: Marketplace, requestId: RequestId, slotIndex: UInt256): bool {.contract, view.}
diff --git a/tests/contracts/testDeployment.nim b/tests/contracts/testDeployment.nim
index 4101b71a..f89e28a8 100644
--- a/tests/contracts/testDeployment.nim
+++ b/tests/contracts/testDeployment.nim
@@ -9,7 +9,7 @@ import ../checktest
 type MockProvider = ref object of Provider
   chainId*: UInt256
 
-method getChainId*(provider: MockProvider): Future[UInt256] {.async.} =
+method getChainId*(provider: MockProvider): Future[UInt256] {.async: (raises:[ProviderError]).} =
   return provider.chainId
 
 proc configFactory(): CodexConf =
diff --git a/tests/contracts/time.nim b/tests/contracts/time.nim
index cd6aac1b..11bd1b6d 100644
--- a/tests/contracts/time.nim
+++ b/tests/contracts/time.nim
@@ -1,4 +1,5 @@
 import pkg/ethers
+import pkg/serde
 
 proc currentTime*(provider: Provider): Future[UInt256] {.async.} =
   return (!await provider.getBlock(BlockTag.pending)).timestamp
diff --git a/vendor/nim-ethers b/vendor/nim-ethers
index 5b170adc..507ac6a4 160000
--- a/vendor/nim-ethers
+++ b/vendor/nim-ethers
@@ -1 +1 @@
-Subproject commit 5b170adcb1ffb1dbb273d1b7679bf3d9a08adb76
+Subproject commit 507ac6a4cc71cec9be7693fa393db4a49b52baf9
diff --git a/vendor/nim-json-rpc b/vendor/nim-json-rpc
index 0bf2bcbe..0408795b 160000
--- a/vendor/nim-json-rpc
+++ b/vendor/nim-json-rpc
@@ -1 +1 @@
-Subproject commit 0bf2bcbe74a18a3c7a709d57108bb7b51e748a92
+Subproject commit 0408795be95c00d75e96eaef6eae8a9c734014f5
diff --git a/vendor/nim-json-serialization b/vendor/nim-json-serialization
index bb53d49c..5127b26e 160000
--- a/vendor/nim-json-serialization
+++ b/vendor/nim-json-serialization
@@ -1 +1 @@
-Subproject commit bb53d49caf2a6c6cf1df365ba84af93cdcfa7aa3
+Subproject commit 5127b26ee58076e9369e7c126c196793c2b12e73
diff --git a/vendor/nim-serde b/vendor/nim-serde
index b1e5e5d3..83e4a2cc 160000
--- a/vendor/nim-serde
+++ b/vendor/nim-serde
@@ -1 +1 @@
-Subproject commit b1e5e5d39a99ea56b750f6d9272dd319f4ad4291
+Subproject commit 83e4a2ccf621d3040c6e7e0267393ca2d205988e
diff --git a/vendor/nim-serialization b/vendor/nim-serialization
index 384eb256..f709bd9e 160000
--- a/vendor/nim-serialization
+++ b/vendor/nim-serialization
@@ -1 +1 @@
-Subproject commit 384eb2561ee755446cff512a8e057325848b86a7
+Subproject commit f709bd9e16b1b6870fe3e4401196479e014a2ef6