diff --git a/codex/node.nim b/codex/node.nim
index c89d0dad..bc23fe7f 100644
--- a/codex/node.nim
+++ b/codex/node.nim
@@ -312,13 +312,13 @@ proc start*(node: CodexNodeRef) {.async.} =
     await node.discovery.start()
 
   if contracts =? node.contracts:
-    contracts.sales.store = proc(cid: string, _: Availability) {.async.} =
+    contracts.sales.onStore = proc(cid: string, _: Availability) {.async.} =
       # store data in local storage
       (await node.store(Cid.init(cid).tryGet())).tryGet()
     contracts.sales.onClear = proc(availability: Availability, request: StorageRequest) =
       # TODO: remove data from local storage
       discard
-    contracts.sales.prove = proc(cid: string): Future[seq[byte]] {.async.} =
+    contracts.sales.onProve = proc(cid: string): Future[seq[byte]] {.async.} =
       # TODO: generate proof
       return @[42'u8]
     await contracts.start()
diff --git a/codex/sales.nim b/codex/sales.nim
index 39fa6ea4..2a9e51c3 100644
--- a/codex/sales.nim
+++ b/codex/sales.nim
@@ -15,8 +15,8 @@ type
     clock: Clock
     subscription: ?Subscription
     available*: seq[Availability]
-    store: ?Store
-    prove: ?Prove
+    onStore: ?OnStore
+    onProve: ?OnProve
     onClear: ?OnClear
     onSale: ?OnSale
   Availability* = object
@@ -34,8 +34,8 @@ type
     running: ?Future[void]
     waiting: ?Future[void]
     finished: bool
-  Store = proc(cid: string, availability: Availability): Future[void] {.gcsafe, upraises: [].}
-  Prove = proc(cid: string): Future[seq[byte]] {.gcsafe, upraises: [].}
+  OnStore = proc(cid: string, availability: Availability): Future[void] {.gcsafe, upraises: [].}
+  OnProve = proc(cid: string): Future[seq[byte]] {.gcsafe, upraises: [].}
   OnClear = proc(availability: Availability, request: StorageRequest) {.gcsafe, upraises: [].}
   OnSale = proc(availability: Availability, request: StorageRequest) {.gcsafe, upraises: [].}
 
@@ -53,11 +53,11 @@ proc init*(_: type Availability,
   doAssert randomBytes(id) == 32
   Availability(id: id, size: size, duration: duration, minPrice: minPrice)
 
-proc `store=`*(sales: Sales, store: Store) =
-  sales.store = some store
+proc `onStore=`*(sales: Sales, onStore: OnStore) =
+  sales.onStore = some onStore
 
-proc `prove=`*(sales: Sales, prove: Prove) =
-  sales.prove = some prove
+proc `onProve=`*(sales: Sales, onProve: OnProve) =
+  sales.onProve = some onProve
 
 proc `onClear=`*(sales: Sales, onClear: OnClear) =
   sales.onClear = some onClear
@@ -129,11 +129,11 @@ proc start(agent: SalesAgent) {.async.} =
     let market = sales.market
     let availability = agent.availability
 
-    without store =? sales.store:
-      raiseAssert "store proc not set"
+    without onStore =? sales.onStore:
+      raiseAssert "onStore callback not set"
 
-    without prove =? sales.prove:
-      raiseAssert "prove proc not set"
+    without onProve =? sales.onProve:
+      raiseAssert "onProve callback not set"
 
     sales.remove(availability)
 
@@ -146,8 +146,8 @@ proc start(agent: SalesAgent) {.async.} =
 
     agent.waiting = some agent.waitForExpiry()
 
-    await store(request.content.cid, availability)
-    let proof = await prove(request.content.cid)
+    await onStore(request.content.cid, availability)
+    let proof = await onProve(request.content.cid)
     await market.fulfillRequest(request.id, proof)
   except CancelledError:
     raise
diff --git a/tests/codex/testsales.nim b/tests/codex/testsales.nim
index a1fd1f4c..b38248e4 100644
--- a/tests/codex/testsales.nim
+++ b/tests/codex/testsales.nim
@@ -32,9 +32,9 @@ suite "Sales":
     market = MockMarket.new()
     clock = MockClock.new()
     sales = Sales.new(market, clock)
-    sales.store = proc(cid: string, availability: Availability) {.async.} =
+    sales.onStore = proc(cid: string, availability: Availability) {.async.} =
       discard
-    sales.prove = proc(cid: string): Future[seq[byte]] {.async.} =
+    sales.onProve = proc(cid: string): Future[seq[byte]] {.async.} =
       return proof
     await sales.start()
     request.expiry = (clock.now() + 42).u256
@@ -79,7 +79,7 @@ suite "Sales":
   test "retrieves and stores data locally":
     var storingCid: string
     var storingAvailability: Availability
-    sales.store = proc(cid: string, availability: Availability) {.async.} =
+    sales.onStore = proc(cid: string, availability: Availability) {.async.} =
       storingCid = cid
       storingAvailability = availability
     sales.add(availability)
@@ -88,7 +88,7 @@ suite "Sales":
 
   test "makes storage available again when data retrieval fails":
     let error = newException(IOError, "data retrieval failed")
-    sales.store = proc(cid: string, availability: Availability) {.async.} =
+    sales.onStore = proc(cid: string, availability: Availability) {.async.} =
       raise error
     sales.add(availability)
     discard await market.requestStorage(request)
@@ -96,7 +96,7 @@ suite "Sales":
 
   test "generates proof of storage":
     var provingCid: string
-    sales.prove = proc(cid: string): Future[seq[byte]] {.async.} = provingCid = cid
+    sales.onProve = proc(cid: string): Future[seq[byte]] {.async.} = provingCid = cid
     sales.add(availability)
     discard await market.requestStorage(request)
     check provingCid == request.content.cid
@@ -121,7 +121,7 @@ suite "Sales":
     check soldRequest == request
 
   test "calls onClear when storage becomes available again":
-    sales.prove = proc(cid: string): Future[seq[byte]] {.async.} =
+    sales.onProve = proc(cid: string): Future[seq[byte]] {.async.} =
       raise newException(IOError, "proof failed")
     var clearedAvailability: Availability
     var clearedRequest: StorageRequest
@@ -135,7 +135,7 @@ suite "Sales":
 
   test "makes storage available again when other host fulfills request":
     let otherHost = Address.example
-    sales.store = proc(cid: string, availability: Availability) {.async.} =
+    sales.onStore = proc(cid: string, availability: Availability) {.async.} =
       await sleepAsync(1.hours)
     sales.add(availability)
     discard await market.requestStorage(request)
@@ -143,7 +143,7 @@ suite "Sales":
     check sales.available == @[availability]
 
   test "makes storage available again when request expires":
-    sales.store = proc(cid: string, availability: Availability) {.async.} =
+    sales.onStore = proc(cid: string, availability: Availability) {.async.} =
       await sleepAsync(1.hours)
     sales.add(availability)
     discard await market.requestStorage(request)