diff --git a/dagger/contracts/clock.nim b/dagger/contracts/clock.nim
index 584c16c4..ed171c92 100644
--- a/dagger/contracts/clock.nim
+++ b/dagger/contracts/clock.nim
@@ -4,6 +4,8 @@ import pkg/chronos
 import pkg/stint
 import ../clock
 
+export clock
+
 type
   OnChainClock* = ref object of Clock
     provider: Provider
diff --git a/dagger/contracts/interactions.nim b/dagger/contracts/interactions.nim
index fd04334b..665b38b6 100644
--- a/dagger/contracts/interactions.nim
+++ b/dagger/contracts/interactions.nim
@@ -7,6 +7,7 @@ import ./deployment
 import ./storage
 import ./market
 import ./proofs
+import ./clock
 
 export purchasing
 export sales
@@ -18,6 +19,7 @@ type
     purchasing*: Purchasing
     sales*: Sales
     proving*: Proving
+    clock: OnChainClock
 
 proc new*(_: type ContractInteractions,
           signer: Signer,
@@ -30,10 +32,12 @@ proc new*(_: type ContractInteractions,
   let contract = Storage.new(address, signer)
   let market = OnChainMarket.new(contract)
   let proofs = OnChainProofs.new(contract)
+  let clock = OnChainClock.new(signer.provider)
   some ContractInteractions(
     purchasing: Purchasing.new(market),
     sales: Sales.new(market),
-    proving: Proving.new(proofs)
+    proving: Proving.new(proofs, clock),
+    clock: clock
   )
 
 proc new*(_: type ContractInteractions,
@@ -65,9 +69,11 @@ proc new*(_: type ContractInteractions): ?ContractInteractions =
   ContractInteractions.new("ws://localhost:8545")
 
 proc start*(interactions: ContractInteractions) {.async.} =
+  await interactions.clock.start()
   await interactions.sales.start()
   await interactions.proving.start()
 
 proc stop*(interactions: ContractInteractions) {.async.} =
   await interactions.sales.stop()
   await interactions.proving.stop()
+  await interactions.clock.stop()
diff --git a/dagger/proving.nim b/dagger/proving.nim
index f711decf..cabd709e 100644
--- a/dagger/proving.nim
+++ b/dagger/proving.nim
@@ -1,9 +1,9 @@
 import std/sets
-import std/times
 import pkg/upraises
 import pkg/questionable
 import pkg/chronicles
 import ./por/timing/proofs
+import ./clock
 
 export sets
 export proofs
@@ -11,13 +11,14 @@ export proofs
 type
   Proving* = ref object
     proofs: Proofs
+    clock: Clock
     loop: ?Future[void]
     contracts*: HashSet[ContractId]
     onProofRequired: ?OnProofRequired
   OnProofRequired* = proc (id: ContractId) {.gcsafe, upraises:[].}
 
-func new*(_: type Proving, proofs: Proofs): Proving =
-  Proving(proofs: proofs)
+func new*(_: type Proving, proofs: Proofs, clock: Clock): Proving =
+  Proving(proofs: proofs, clock: clock)
 
 proc `onProofRequired=`*(proving: Proving, callback: OnProofRequired) =
   proving.onProofRequired = some callback
@@ -26,7 +27,7 @@ func add*(proving: Proving, id: ContractId) =
   proving.contracts.incl(id)
 
 proc removeEndedContracts(proving: Proving) {.async.} =
-  let now = getTime().toUnix().u256
+  let now = proving.clock.now().u256
   var ended: HashSet[ContractId]
   for id in proving.contracts:
     if now >= (await proving.proofs.getProofEnd(id)):
diff --git a/tests/dagger/helpers/mockclock.nim b/tests/dagger/helpers/mockclock.nim
new file mode 100644
index 00000000..6ff8a411
--- /dev/null
+++ b/tests/dagger/helpers/mockclock.nim
@@ -0,0 +1,21 @@
+import std/times
+import dagger/clock
+
+export clock
+
+type
+  MockClock* = ref object of Clock
+    time: SecondsSince1970
+
+func new*(_: type MockClock,
+          time: SecondsSince1970 = getTime().toUnix): MockClock =
+  MockClock(time: time)
+
+func set*(clock: MockClock, time: SecondsSince1970) =
+  clock.time = time
+
+func advance*(clock: MockClock, seconds: int64) =
+  clock.time += seconds
+
+method now*(clock: MockClock): SecondsSince1970 =
+  clock.time
diff --git a/tests/dagger/testproving.nim b/tests/dagger/testproving.nim
index 29e000f7..419dec16 100644
--- a/tests/dagger/testproving.nim
+++ b/tests/dagger/testproving.nim
@@ -1,18 +1,20 @@
-from std/times import getTime, toUnix
 import pkg/asynctest
 import pkg/chronos
 import pkg/dagger/proving
 import ./helpers/mockproofs
+import ./helpers/mockclock
 import ./examples
 
 suite "Proving":
 
   var proving: Proving
   var proofs: MockProofs
+  var clock: MockClock
 
   setup:
     proofs = MockProofs.new()
-    proving = Proving.new(proofs)
+    clock = MockClock.new()
+    proving = Proving.new(proofs, clock)
     await proving.start()
 
   teardown:
@@ -80,7 +82,7 @@ suite "Proving":
   test "stops watching when contract has ended":
     let id = ContractId.example
     proving.add(id)
-    proofs.setProofEnd(id, getTime().toUnix().u256)
+    proofs.setProofEnd(id, clock.now().u256)
     await proofs.advanceToNextPeriod()
     var called: bool
     proc onProofRequired(id: ContractId) =