diff --git a/codex/contracts/requests.nim b/codex/contracts/requests.nim
index 1363fb9d..946b59af 100644
--- a/codex/contracts/requests.nim
+++ b/codex/contracts/requests.nim
@@ -19,6 +19,7 @@ type
     content* {.serialize.}: StorageContent
     expiry* {.serialize.}: UInt256
     nonce*: Nonce
+    expansionRate* {.serialize.}: uint8
   StorageAsk* = object
     slots* {.serialize.}: uint64
     slotSize* {.serialize.}: UInt256
@@ -93,7 +94,8 @@ func fromTuple(_: type StorageRequest, tupl: tuple): StorageRequest =
     ask: tupl[1],
     content: tupl[2],
     expiry: tupl[3],
-    nonce: tupl[4]
+    nonce: tupl[4],
+    expansionRate: tupl[5],
   )
 
 func fromTuple(_: type Slot, tupl: tuple): Slot =
diff --git a/codex/node.nim b/codex/node.nim
index 88305a08..fc6d15f8 100644
--- a/codex/node.nim
+++ b/codex/node.nim
@@ -394,7 +394,8 @@ proc setupRequest(
   tolerance: uint,
   reward: UInt256,
   collateral: UInt256,
-  expiry:  UInt256): Future[?!StorageRequest] {.async.} =
+  expiry:  UInt256,
+  expansionRate: uint8): Future[?!StorageRequest] {.async.} =
   ## Setup slots for a given dataset
   ##
 
@@ -411,6 +412,7 @@ proc setupRequest(
     proofProbability  = proofProbability
     collateral        = collateral
     expiry            = expiry
+    expansionRate     = expansionRate
     ecK               = ecK
     ecM               = ecM
 
@@ -474,7 +476,8 @@ proc setupRequest(
         cid: $manifestBlk.cid, # TODO: why string?
         merkleRoot: verifyRoot
       ),
-      expiry: expiry
+      expiry: expiry,
+      expansionRate: expansionRate
     )
 
   trace "Request created", request = $request
@@ -489,7 +492,8 @@ proc requestStorage*(
   tolerance: uint,
   reward: UInt256,
   collateral: UInt256,
-  expiry:  UInt256): Future[?!PurchaseId] {.async.} =
+  expiry:  UInt256,
+  expansionRate: uint8): Future[?!PurchaseId] {.async.} =
   ## Initiate a request for storage sequence, this might
   ## be a multistep procedure.
   ##
@@ -503,6 +507,7 @@ proc requestStorage*(
     proofProbability  = proofProbability
     collateral        = collateral
     expiry            = expiry.truncate(int64)
+    expansionRate     = expansionRate
     now               = self.clock.now
 
   trace "Received a request for storage!"
@@ -520,7 +525,8 @@ proc requestStorage*(
       tolerance,
       reward,
       collateral,
-      expiry)), err:
+      expiry,
+      expansionRate)), err:
     trace "Unable to setup request"
     return failure err
 
diff --git a/codex/rest/api.nim b/codex/rest/api.nim
index 8197d8d4..67f7e36c 100644
--- a/codex/rest/api.nim
+++ b/codex/rest/api.nim
@@ -455,6 +455,7 @@ proc initPurchasingApi(node: CodexNodeRef, router: var RestRouter) =
 
         let nodes = params.nodes |? 1
         let tolerance = params.tolerance |? 0
+        let expansionRate = params.expansionRate |? 60'u8
 
         # prevent underflow
         if tolerance > nodes:
@@ -473,6 +474,9 @@ proc initPurchasingApi(node: CodexNodeRef, router: var RestRouter) =
         if expiry <= 0 or expiry >= params.duration:
           return RestApiResponse.error(Http400, "Expiry needs value bigger then zero and smaller then the request's duration", headers = headers)
 
+        if expansionRate > 100'u8:
+          return RestApiResponse.error(Http400, "Expansion rate must be between 0 and 100 (inclusive)", headers = headers)
+
         without purchaseId =? await node.requestStorage(
           cid,
           params.duration,
@@ -481,7 +485,8 @@ proc initPurchasingApi(node: CodexNodeRef, router: var RestRouter) =
           tolerance,
           params.reward,
           params.collateral,
-          expiry), error:
+          expiry,
+          expansionRate), error:
 
           if error of InsufficientBlocksError:
             return RestApiResponse.error(Http400,
diff --git a/codex/rest/json.nim b/codex/rest/json.nim
index fba708be..ac9a5a04 100644
--- a/codex/rest/json.nim
+++ b/codex/rest/json.nim
@@ -20,6 +20,7 @@ type
     expiry* {.serialize.}: ?UInt256
     nodes* {.serialize.}: ?uint
     tolerance* {.serialize.}: ?uint
+    expansionRate* {.serialize.}: ?uint8
 
   RestPurchase* = object
     requestId* {.serialize.}: RequestId
diff --git a/tests/codex/node/testnode.nim b/tests/codex/node/testnode.nim
index ab8317ec..0f9ef8b5 100644
--- a/tests/codex/node/testnode.nim
+++ b/tests/codex/node/testnode.nim
@@ -164,7 +164,8 @@ asyncchecksuite "Test Node - Basic":
         reward = 2.u256,
         proofProbability = 3.u256,
         expiry = 200.u256,
-        collateral = 200.u256)).tryGet
+        collateral = 200.u256,
+        expansionRate = 100'u8)).tryGet
 
     check:
       (await verifiableBlock.cid in localStore) == true
diff --git a/tests/examples.nim b/tests/examples.nim
index 17391e1a..28e0ac3f 100644
--- a/tests/examples.nim
+++ b/tests/examples.nim
@@ -60,6 +60,7 @@ proc example*(_: type StorageRequest): StorageRequest =
       merkleRoot: array[32, byte].example
     ),
     expiry:(60 * 60).u256, # 1 hour ,
+    expansionRate: 100'u8,
     nonce: Nonce.example
   )
 
diff --git a/tests/integration/codexclient.nim b/tests/integration/codexclient.nim
index d2d78b46..5aa2c8bd 100644
--- a/tests/integration/codexclient.nim
+++ b/tests/integration/codexclient.nim
@@ -97,7 +97,8 @@ proc requestStorageRaw*(
     collateral: UInt256,
     expiry: uint = 0,
     nodes: uint = 2,
-    tolerance: uint = 0
+    tolerance: uint = 0,
+    expansionRate: uint8 = 100
 ): Response =
 
   ## Call request storage REST endpoint
@@ -109,7 +110,8 @@ proc requestStorageRaw*(
       "proofProbability": proofProbability,
       "collateral": collateral,
       "nodes": nodes,
-      "tolerance": tolerance
+      "tolerance": tolerance,
+      "expansionRate": expansionRate
     }
 
   if expiry != 0:
@@ -126,11 +128,12 @@ proc requestStorage*(
     expiry: uint,
     collateral: UInt256,
     nodes: uint = 2,
-    tolerance: uint = 0
+    tolerance: uint = 0,
+    expansionRate: uint8 = 100
 ): ?!PurchaseId =
   ## Call request storage REST endpoint
   ##
-  let response = client.requestStorageRaw(cid, duration, reward, proofProbability, collateral, expiry, nodes, tolerance)
+  let response = client.requestStorageRaw(cid, duration, reward, proofProbability, collateral, expiry, nodes, tolerance, expansionRate)
   if response.status != "200 OK":
     doAssert(false, response.body)
   PurchaseId.fromHex(response.body).catch
diff --git a/tests/integration/testrestapi.nim b/tests/integration/testrestapi.nim
index 1834dcf2..6cc401ee 100644
--- a/tests/integration/testrestapi.nim
+++ b/tests/integration/testrestapi.nim
@@ -105,6 +105,25 @@ twonodessuite "REST API", debug1 = false, debug2 = false:
       check responseBefore.status == "400 Bad Request"
       check responseBefore.body == "Invalid parameters: `tolerance` cannot be greater than `nodes`"
 
+
+  test "request storage fails when expansionRate is too large":
+    let data = await RandomChunker.example(blocks=2)
+    let cid = client1.upload(data).get
+    let response = client1.requestStorageRaw(
+      cid,
+      duration=10.u256,
+      reward=2.u256,
+      proofProbability=3.u256,
+      nodes=2,
+      tolerance=0,
+      collateral=200.u256,
+      expiry=9,
+      expansionRate=101)
+
+    check:
+      response.status == "400 Bad Request"
+      response.body == "Expansion rate must be between 0 and 100 (inclusive)"
+
   test "request storage succeeds if nodes and tolerance within range":
     let data = await RandomChunker.example(blocks=2)
     let cid = client1.upload(data).get
diff --git a/vendor/codex-contracts-eth b/vendor/codex-contracts-eth
index d2ba8693..2331ae1f 160000
--- a/vendor/codex-contracts-eth
+++ b/vendor/codex-contracts-eth
@@ -1 +1 @@
-Subproject commit d2ba8693e772b83e80746ffadc1efc36c836caf0
+Subproject commit 2331ae1f0ada27bb1a9fe61d7432033ef0ab5d81