diff --git a/pkg/core/blockchain_test.go b/pkg/core/blockchain_test.go
index 9a1c38562..a2fcc188e 100644
--- a/pkg/core/blockchain_test.go
+++ b/pkg/core/blockchain_test.go
@@ -6,7 +6,7 @@ import (
 
 	"github.com/CityOfZion/neo-go/config"
 	"github.com/CityOfZion/neo-go/pkg/core/storage"
-	"github.com/CityOfZion/neo-go/pkg/util"
+	"github.com/CityOfZion/neo-go/pkg/io"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -142,10 +142,10 @@ func TestGetTransaction(t *testing.T) {
 	assert.Equal(t, block.Index, height)
 	assert.Equal(t, block.Transactions[0], tx)
 	assert.Equal(t, 10, tx.Size())
-	assert.Equal(t, 1, util.GetVarSize(tx.Attributes))
-	assert.Equal(t, 1, util.GetVarSize(tx.Inputs))
-	assert.Equal(t, 1, util.GetVarSize(tx.Outputs))
-	assert.Equal(t, 1, util.GetVarSize(tx.Scripts))
+	assert.Equal(t, 1, io.GetVarSize(tx.Attributes))
+	assert.Equal(t, 1, io.GetVarSize(tx.Inputs))
+	assert.Equal(t, 1, io.GetVarSize(tx.Outputs))
+	assert.Equal(t, 1, io.GetVarSize(tx.Scripts))
 }
 
 func newTestChain(t *testing.T) *Blockchain {
diff --git a/pkg/core/transaction/attribute.go b/pkg/core/transaction/attribute.go
index b4e07aee4..3c60d3d5f 100644
--- a/pkg/core/transaction/attribute.go
+++ b/pkg/core/transaction/attribute.go
@@ -6,7 +6,6 @@ import (
 	"fmt"
 
 	"github.com/CityOfZion/neo-go/pkg/io"
-	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 // Attribute represents a Transaction attribute.
@@ -87,7 +86,7 @@ func (attr *Attribute) Size() int {
 	case DescriptionURL:
 		sz += 1 + len(attr.Data)
 	default:
-		sz += util.GetVarSize(attr.Data)
+		sz += io.GetVarSize(attr.Data)
 	}
 	return sz
 }
diff --git a/pkg/core/transaction/claim.go b/pkg/core/transaction/claim.go
index bb864548c..6c1a69eda 100644
--- a/pkg/core/transaction/claim.go
+++ b/pkg/core/transaction/claim.go
@@ -2,7 +2,6 @@ package transaction
 
 import (
 	"github.com/CityOfZion/neo-go/pkg/io"
-	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 // ClaimTX represents a claim transaction.
@@ -42,7 +41,7 @@ func (tx *ClaimTX) EncodeBinary(bw *io.BinWriter) error {
 
 // Size returns serialized binary size for this transaction.
 func (tx *ClaimTX) Size() int {
-	sz := util.GetVarSize(uint64(len(tx.Claims)))
+	sz := io.GetVarSize(uint64(len(tx.Claims)))
 	for _, claim := range tx.Claims {
 		sz += claim.Size()
 	}
diff --git a/pkg/core/transaction/invocation.go b/pkg/core/transaction/invocation.go
index 52a105bcb..bfdf3df66 100644
--- a/pkg/core/transaction/invocation.go
+++ b/pkg/core/transaction/invocation.go
@@ -53,7 +53,7 @@ func (tx *InvocationTX) EncodeBinary(bw *io.BinWriter) error {
 
 // Size returns serialized binary size for this transaction.
 func (tx *InvocationTX) Size() int {
-	sz := util.GetVarSize(tx.Script)
+	sz := io.GetVarSize(tx.Script)
 	if tx.Version >= 1 {
 		sz += tx.Gas.Size()
 	}
diff --git a/pkg/core/transaction/publish.go b/pkg/core/transaction/publish.go
index c5149bc97..fbf3d11d6 100644
--- a/pkg/core/transaction/publish.go
+++ b/pkg/core/transaction/publish.go
@@ -3,7 +3,6 @@ package transaction
 import (
 	"github.com/CityOfZion/neo-go/pkg/io"
 	"github.com/CityOfZion/neo-go/pkg/smartcontract"
-	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 // PublishTX represents a publish transaction.
@@ -73,14 +72,14 @@ func (tx *PublishTX) EncodeBinary(bw *io.BinWriter) error {
 
 // Size returns serialized binary size for this transaction.
 func (tx *PublishTX) Size() int {
-	sz := util.GetVarSize(tx.Script) + util.GetVarSize(uint64(len(tx.ParamList)))
+	sz := io.GetVarSize(tx.Script) + io.GetVarSize(uint64(len(tx.ParamList)))
 	sz += 1 * len(tx.ParamList)
 	sz++
 	if tx.Version >= 1 {
 		sz++
 	}
-	sz += util.GetVarSize(tx.Name) + util.GetVarSize(tx.CodeVersion)
-	sz += util.GetVarSize(tx.Author) + util.GetVarSize(tx.Email)
-	sz += util.GetVarSize(tx.Description)
+	sz += io.GetVarSize(tx.Name) + io.GetVarSize(tx.CodeVersion)
+	sz += io.GetVarSize(tx.Author) + io.GetVarSize(tx.Email)
+	sz += io.GetVarSize(tx.Description)
 	return sz
 }
diff --git a/pkg/core/transaction/register.go b/pkg/core/transaction/register.go
index 711cb7465..1d45aa23e 100644
--- a/pkg/core/transaction/register.go
+++ b/pkg/core/transaction/register.go
@@ -62,5 +62,5 @@ func (tx *RegisterTX) EncodeBinary(bw *io.BinWriter) error {
 
 // Size returns serialized binary size for this transaction.
 func (tx *RegisterTX) Size() int {
-	return 1 + util.GetVarSize(tx.Name) + tx.Amount.Size() + 1 + len(tx.Owner.Bytes()) + tx.Admin.Size()
+	return 1 + io.GetVarSize(tx.Name) + tx.Amount.Size() + 1 + len(tx.Owner.Bytes()) + tx.Admin.Size()
 }
diff --git a/pkg/core/transaction/state.go b/pkg/core/transaction/state.go
index 490c8f6a2..be52ef734 100644
--- a/pkg/core/transaction/state.go
+++ b/pkg/core/transaction/state.go
@@ -2,7 +2,6 @@ package transaction
 
 import (
 	"github.com/CityOfZion/neo-go/pkg/io"
-	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 // StateTX represents a state transaction.
@@ -38,7 +37,7 @@ func (tx *StateTX) EncodeBinary(w *io.BinWriter) error {
 
 // Size returns serialized binary size for this transaction.
 func (tx *StateTX) Size() int {
-	sz := util.GetVarSize(uint64(len(tx.Descriptors)))
+	sz := io.GetVarSize(uint64(len(tx.Descriptors)))
 	for _, desc := range tx.Descriptors {
 		sz += desc.Size()
 	}
diff --git a/pkg/core/transaction/state_descriptor.go b/pkg/core/transaction/state_descriptor.go
index c7e82822e..4c794fceb 100644
--- a/pkg/core/transaction/state_descriptor.go
+++ b/pkg/core/transaction/state_descriptor.go
@@ -2,7 +2,6 @@ package transaction
 
 import (
 	"github.com/CityOfZion/neo-go/pkg/io"
-	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 // DescStateType represents the type of StateDescriptor.
@@ -44,5 +43,5 @@ func (s *StateDescriptor) EncodeBinary(w *io.BinWriter) error {
 
 // Size returns serialized binary size for state descriptor.
 func (s *StateDescriptor) Size() int {
-	return 1 + util.GetVarSize(s.Key) + util.GetVarSize(s.Value) + util.GetVarSize(s.Field)
+	return 1 + io.GetVarSize(s.Key) + io.GetVarSize(s.Value) + io.GetVarSize(s.Field)
 }
diff --git a/pkg/core/transaction/transaction.go b/pkg/core/transaction/transaction.go
index 3bf651317..cd9e3c352 100644
--- a/pkg/core/transaction/transaction.go
+++ b/pkg/core/transaction/transaction.go
@@ -265,10 +265,10 @@ func (t Transaction) GroupOutputByAssetID() map[util.Uint256][]*Output {
 
 // Size returns the size of the transaction in term of bytes
 func (t *Transaction) Size() int {
-	attrSize := util.GetVarSize(t.Attributes)
-	inputSize := util.GetVarSize(t.Inputs)
-	outputSize := util.GetVarSize(t.Outputs)
-	witnesSize := util.GetVarSize(t.Scripts)
+	attrSize := io.GetVarSize(t.Attributes)
+	inputSize := io.GetVarSize(t.Inputs)
+	outputSize := io.GetVarSize(t.Outputs)
+	witnesSize := io.GetVarSize(t.Scripts)
 	// uint8 + uint8 + attrSize + inputSize + outputSize + witnesSize
 	return 2 + attrSize + inputSize + outputSize + witnesSize + t.Data.Size()
 }
diff --git a/pkg/core/transaction/witness.go b/pkg/core/transaction/witness.go
index 20c1d8d91..d4da3836a 100644
--- a/pkg/core/transaction/witness.go
+++ b/pkg/core/transaction/witness.go
@@ -42,7 +42,7 @@ func (w *Witness) MarshalJSON() ([]byte, error) {
 
 // Size returns the size in bytes of the Witness.
 func (w *Witness) Size() int {
-	return util.GetVarSize(w.InvocationScript) + util.GetVarSize(w.VerificationScript)
+	return io.GetVarSize(w.InvocationScript) + io.GetVarSize(w.VerificationScript)
 }
 
 // ScriptHash returns the hash of the VerificationScript.
diff --git a/pkg/util/size.go b/pkg/io/size.go
similarity index 94%
rename from pkg/util/size.go
rename to pkg/io/size.go
index 33b7b60fc..bde30be19 100644
--- a/pkg/util/size.go
+++ b/pkg/io/size.go
@@ -1,10 +1,8 @@
-package util
+package io
 
 import (
 	"fmt"
 	"reflect"
-
-	"github.com/CityOfZion/neo-go/pkg/io"
 )
 
 var (
@@ -67,9 +65,9 @@ func GetVarSize(value interface{}) int {
 
 		if valueLength != 0 {
 			switch reflect.ValueOf(value).Index(0).Interface().(type) {
-			case io.Serializable:
+			case Serializable:
 				for i := 0; i < valueLength; i++ {
-					elem := v.Index(i).Interface().(io.Serializable)
+					elem := v.Index(i).Interface().(Serializable)
 					valueSize += elem.Size()
 				}
 			case uint8, int8:
diff --git a/pkg/util/size_test.go b/pkg/io/size_test.go
similarity index 91%
rename from pkg/util/size_test.go
rename to pkg/io/size_test.go
index d77ceaebc..e3028accd 100644
--- a/pkg/util/size_test.go
+++ b/pkg/io/size_test.go
@@ -1,10 +1,10 @@
-package util
+package io
 
 import (
 	"fmt"
 	"testing"
 
-	"github.com/CityOfZion/neo-go/pkg/io"
+	"github.com/CityOfZion/neo-go/pkg/util"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -12,11 +12,11 @@ import (
 type smthSerializable struct {
 }
 
-func (*smthSerializable) DecodeBinary(*io.BinReader) error {
+func (*smthSerializable) DecodeBinary(*BinReader) error {
 	return nil
 }
 
-func (*smthSerializable) EncodeBinary(*io.BinWriter) error {
+func (*smthSerializable) EncodeBinary(*BinWriter) error {
 	return nil
 }
 
@@ -87,7 +87,7 @@ func TestVarSize(t *testing.T) {
 		},
 		{
 			// The neo C# implementation doe not allowed this!
-			Uint160{1, 2, 4, 5, 6},
+			util.Uint160{1, 2, 4, 5, 6},
 			"test_Uint160_1",
 			21,
 		},
@@ -153,7 +153,7 @@ func TestVarSize(t *testing.T) {
 			241,
 		},
 		// The neo C# implementation doe not allowed this!
-		{Uint256{1, 2, 3, 4, 5, 6},
+		{util.Uint256{1, 2, 3, 4, 5, 6},
 			"test_Uint256_1",
 			33,
 		},
diff --git a/pkg/network/payload/version.go b/pkg/network/payload/version.go
index b9d347d45..de78b1b3b 100644
--- a/pkg/network/payload/version.go
+++ b/pkg/network/payload/version.go
@@ -4,7 +4,6 @@ import (
 	"time"
 
 	"github.com/CityOfZion/neo-go/pkg/io"
-	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 // Size of the payload not counting UserAgent encoding (which is at least 1 byte
@@ -83,5 +82,5 @@ func (p *Version) EncodeBinary(br *io.BinWriter) error {
 
 // Size implements the payloader interface.
 func (p *Version) Size() uint32 {
-	return uint32(minVersionSize + util.GetVarSize(p.UserAgent))
+	return uint32(minVersionSize + io.GetVarSize(p.UserAgent))
 }