diff --git a/nimbus/vm/evmc_host.nim b/nimbus/vm/evmc_host.nim
index 72c7d6f91..6686dbd22 100644
--- a/nimbus/vm/evmc_host.nim
+++ b/nimbus/vm/evmc_host.nim
@@ -116,25 +116,20 @@ proc hostEmitLogImpl(ctx: Computation, address: EthAddress,
     for i in 0 ..< topicsCount:
       log.topics[i] = topics[i].bytes
 
-  if dataSize > 0:
-    log.data = newSeq[byte](dataSize)
-    copyMem(log.data[0].addr, data, dataSize)
-
+  log.data = @makeOpenArray(data, dataSize)
   log.address = address
   ctx.addLogEntry(log)
 
 template createImpl(c: Computation, m: nimbus_message, res: nimbus_result) =
   # TODO: use evmc_message to evoid copy
-  var childMsg = Message(
+  let childMsg = Message(
     kind: CallKind(m.kind),
     depth: m.depth,
     gas: m.gas,
     sender: m.sender,
-    value: Uint256.fromEvmc(m.value)
+    value: Uint256.fromEvmc(m.value),
+    data: @makeOpenArray(m.inputData, m.inputSize.int)
     )
-  if m.input_size.int > 0:
-    childMsg.data = newSeq[byte](m.input_size.int)
-    copyMem(childMsg.data[0].addr, m.input_data, m.input_size.int)
 
   let child = newComputation(c.vmState, childMsg, Uint256.fromEvmc(m.create2_salt))
   child.execCreate()
@@ -149,13 +144,14 @@ template createImpl(c: Computation, m: nimbus_message, res: nimbus_result) =
   else:
     res.status_code = if child.shouldBurnGas: EVMC_FAILURE else: EVMC_REVERT
     if child.output.len > 0:
+      # TODO: can we move the ownership of seq to raw pointer?
       res.output_size = child.output.len.uint
       res.output_data = cast[ptr byte](alloc(child.output.len))
       copyMem(res.output_data, child.output[0].addr, child.output.len)
       res.release = hostReleaseResultImpl
 
 template callImpl(c: Computation, m: nimbus_message, res: nimbus_result) =
-  var childMsg = Message(
+  let childMsg = Message(
     kind: CallKind(m.kind),
     depth: m.depth,
     gas: m.gas,
@@ -163,13 +159,10 @@ template callImpl(c: Computation, m: nimbus_message, res: nimbus_result) =
     codeAddress: m.destination,
     contractAddress: if m.kind == EVMC_CALL: m.destination else: c.msg.contractAddress,
     value: Uint256.fromEvmc(m.value),
+    data: @makeOpenArray(m.inputData, m.inputSize.int)
     flags: MsgFlags(m.flags)
     )
 
-  if m.input_size.int > 0:
-    childMsg.data = newSeq[byte](m.input_size.int)
-    copyMem(childMsg.data[0].addr, m.input_data, m.input_size.int)
-
   let child = newComputation(c.vmState, childMsg)
   child.execCall()
 
@@ -183,6 +176,7 @@ template callImpl(c: Computation, m: nimbus_message, res: nimbus_result) =
     res.status_code = if child.shouldBurnGas: EVMC_FAILURE else: EVMC_REVERT
 
   if child.output.len > 0:
+    # TODO: can we move the ownership of seq to raw pointer?
     res.output_size = child.output.len.uint
     res.output_data = cast[ptr byte](alloc(child.output.len))
     copyMem(res.output_data, child.output[0].addr, child.output.len)
diff --git a/nimbus/vm/interpreter/opcodes_impl.nim b/nimbus/vm/interpreter/opcodes_impl.nim
index b1c9bf42f..1efd15a2a 100644
--- a/nimbus/vm/interpreter/opcodes_impl.nim
+++ b/nimbus/vm/interpreter/opcodes_impl.nim
@@ -7,7 +7,7 @@
 
 import
   strformat, times, sets, stew/ranges, sequtils, options,
-  chronicles, stint, nimcrypto, stew/ranges/typedranges, eth/common,
+  chronicles, stint, nimcrypto, stew/ranges/[typedranges, ptr_arith], eth/common,
   ./utils/[macros_procs_opcodes, utils_numeric],
   ./gas_meter, ./gas_costs, ./opcode_values, ./vm_forks,
   ../memory, ../message, ../stack, ../code_stream, ../computation,
@@ -606,10 +606,7 @@ template genCreate(callName: untyped, opCode: Op): untyped =
       )
 
       var res = c.host.call(msg)
-      if res.output_size.int > 0:
-        c.returnData = newSeq[byte](res.output_size.int)
-        copyMem(c.returnData[0].addr, res.output_data, c.returnData.len)
-
+      c.returnData = @makeOpenArray(res.outputData, res.outputSize.int)
       c.gasMeter.returnGas(res.gas_left)
 
       if res.status_code == EVMC_SUCCESS:
@@ -775,9 +772,7 @@ template genCall(callName: untyped, opCode: Op): untyped =
       )
 
       var res = c.host.call(msg)
-      if res.output_size.int > 0:
-        c.returnData = newSeq[byte](res.output_size.int)
-        copyMem(c.returnData[0].addr, res.output_data, c.returnData.len)
+      c.returnData = @makeOpenArray(res.outputData, res.outputSize.int)
 
       let actualOutputSize = min(memOutLen, c.returnData.len)
       if actualOutputSize > 0:
diff --git a/nimbus/vm/precompiles.nim b/nimbus/vm/precompiles.nim
index 9c4951006..3fe08b642 100644
--- a/nimbus/vm/precompiles.nim
+++ b/nimbus/vm/precompiles.nim
@@ -245,10 +245,8 @@ proc bn256ecAdd*(computation: Computation, fork: Fork = FkByzantium) =
     input: array[128, byte]
     output: array[64, byte]
   # Padding data
-  let msglen = len(computation.msg.data)
-  let tocopy = if msglen < 128: msglen else: 128
-  if tocopy > 0:
-    copyMem(addr input[0], addr computation.msg.data[0], tocopy)
+  let len = min(computation.msg.data.len, 128) - 1
+  input[0..len] = computation.msg.data[0..len]
   var p1 = G1.getPoint(input.toOpenArray(0, 63))
   var p2 = G1.getPoint(input.toOpenArray(64, 127))
   var apo = (p1 + p2).toAffine()
@@ -267,11 +265,8 @@ proc bn256ecMul*(computation: Computation, fork: Fork = FkByzantium) =
     output: array[64, byte]
 
   # Padding data
-  let msglen = len(computation.msg.data)
-  let tocopy = if msglen < 96: msglen else: 96
-  if tocopy > 0:
-    copyMem(addr input[0], addr computation.msg.data[0], tocopy)
-
+  let len = min(computation.msg.data.len, 96) - 1
+  input[0..len] = computation.msg.data[0..len]
   var p1 = G1.getPoint(input.toOpenArray(0, 63))
   var fr = getFR(input.toOpenArray(64, 95))
   var apo = (p1 * fr).toAffine()