diff --git a/pkg/compiler/syscall_test.go b/pkg/compiler/syscall_test.go
index fdb2f7228..ace3adb1b 100644
--- a/pkg/compiler/syscall_test.go
+++ b/pkg/compiler/syscall_test.go
@@ -98,7 +98,6 @@ func TestSyscallExecution(t *testing.T) {
 		"storage.GetContext":                 {interopnames.SystemStorageGetContext, nil, false},
 		"storage.GetReadOnlyContext":         {interopnames.SystemStorageGetReadOnlyContext, nil, false},
 		"storage.Put":                        {interopnames.SystemStoragePut, []string{sctx, b, b}, true},
-		"storage.PutEx":                      {interopnames.SystemStoragePutEx, []string{sctx, b, b, "storage.PutConstant"}, true},
 		"storage.ConvertContextToReadOnly":   {interopnames.SystemStorageAsReadOnly, []string{sctx}, false},
 		"crypto.ECDsaSecp256r1Verify":        {interopnames.NeoCryptoVerifyWithECDsaSecp256r1, []string{b, pub, sig}, false},
 		"crypto.ECDsaSecp256k1Verify":        {interopnames.NeoCryptoVerifyWithECDsaSecp256k1, []string{b, pub, sig}, false},
diff --git a/pkg/core/interop/interopnames/names.go b/pkg/core/interop/interopnames/names.go
index c15dba958..d342284f1 100644
--- a/pkg/core/interop/interopnames/names.go
+++ b/pkg/core/interop/interopnames/names.go
@@ -46,7 +46,6 @@ const (
 	SystemStorageGetContext                  = "System.Storage.GetContext"
 	SystemStorageGetReadOnlyContext          = "System.Storage.GetReadOnlyContext"
 	SystemStoragePut                         = "System.Storage.Put"
-	SystemStoragePutEx                       = "System.Storage.PutEx"
 	SystemStorageAsReadOnly                  = "System.Storage.AsReadOnly"
 	NeoCryptoVerifyWithECDsaSecp256r1        = "Neo.Crypto.VerifyWithECDsaSecp256r1"
 	NeoCryptoVerifyWithECDsaSecp256k1        = "Neo.Crypto.VerifyWithECDsaSecp256k1"
@@ -101,7 +100,6 @@ var names = []string{
 	SystemStorageGetContext,
 	SystemStorageGetReadOnlyContext,
 	SystemStoragePut,
-	SystemStoragePutEx,
 	SystemStorageAsReadOnly,
 	NeoCryptoVerifyWithECDsaSecp256r1,
 	NeoCryptoVerifyWithECDsaSecp256k1,
diff --git a/pkg/core/interop_system.go b/pkg/core/interop_system.go
index 11f58482e..f66f1df3c 100644
--- a/pkg/core/interop_system.go
+++ b/pkg/core/interop_system.go
@@ -73,10 +73,6 @@ func storageDelete(ic *interop.Context) error {
 	}
 	ic.VM.AddGas(ic.Chain.GetPolicer().GetStoragePrice())
 	key := ic.VM.Estack().Pop().Bytes()
-	si := ic.DAO.GetStorageItem(stc.ID, key)
-	if si != nil && si.IsConst {
-		return errors.New("storage item is constant")
-	}
 	return ic.DAO.DeleteStorageItem(stc.ID, key)
 }
 
@@ -122,7 +118,7 @@ func storageGetContextInternal(ic *interop.Context, isReadOnly bool) error {
 	return nil
 }
 
-func putWithContextAndFlags(ic *interop.Context, stc *StorageContext, key []byte, value []byte, isConst bool) error {
+func putWithContext(ic *interop.Context, stc *StorageContext, key []byte, value []byte) error {
 	if len(key) > MaxStorageKeyLen {
 		return errors.New("key is too big")
 	}
@@ -133,17 +129,14 @@ func putWithContextAndFlags(ic *interop.Context, stc *StorageContext, key []byte
 		return errors.New("StorageContext is read only")
 	}
 	si := ic.DAO.GetStorageItem(stc.ID, key)
-	if si != nil && si.IsConst {
-		return errors.New("storage item exists and is read-only")
-	}
-	sizeInc := 1
+	sizeInc := len(value)
 	if si == nil {
 		si = &state.StorageItem{}
 		sizeInc = len(key) + len(value)
 	} else if len(value) != 0 {
 		if len(value) <= len(si.Value) {
 			sizeInc = (len(value)-1)/4 + 1
-		} else {
+		} else if len(si.Value) != 0 {
 			sizeInc = (len(si.Value)-1)/4 + 1 + len(value) - len(si.Value)
 		}
 	}
@@ -151,12 +144,11 @@ func putWithContextAndFlags(ic *interop.Context, stc *StorageContext, key []byte
 		return errGasLimitExceeded
 	}
 	si.Value = value
-	si.IsConst = isConst
 	return ic.DAO.PutStorageItem(stc.ID, key, si)
 }
 
-// storagePutInternal is a unified implementation of storagePut and storagePutEx.
-func storagePutInternal(ic *interop.Context, getFlag bool) error {
+// storagePut puts key-value pair into the storage.
+func storagePut(ic *interop.Context) error {
 	stcInterface := ic.VM.Estack().Pop().Value()
 	stc, ok := stcInterface.(*StorageContext)
 	if !ok {
@@ -164,21 +156,7 @@ func storagePutInternal(ic *interop.Context, getFlag bool) error {
 	}
 	key := ic.VM.Estack().Pop().Bytes()
 	value := ic.VM.Estack().Pop().Bytes()
-	var flag int
-	if getFlag {
-		flag = int(ic.VM.Estack().Pop().BigInt().Int64())
-	}
-	return putWithContextAndFlags(ic, stc, key, value, int(Constant)&flag != 0)
-}
-
-// storagePut puts key-value pair into the storage.
-func storagePut(ic *interop.Context) error {
-	return storagePutInternal(ic, false)
-}
-
-// storagePutEx puts key-value pair with given flags into the storage.
-func storagePutEx(ic *interop.Context) error {
-	return storagePutInternal(ic, true)
+	return putWithContext(ic, stc, key, value)
 }
 
 // storageContextAsReadOnly sets given context to read-only mode.
diff --git a/pkg/core/interop_system_test.go b/pkg/core/interop_system_test.go
index ff9e936df..ff2d090f8 100644
--- a/pkg/core/interop_system_test.go
+++ b/pkg/core/interop_system_test.go
@@ -277,21 +277,6 @@ func TestStoragePut(t *testing.T) {
 			initVM(t, []byte{1}, make([]byte, MaxStorageValueLen+1), -1)
 			require.Error(t, storagePut(ic))
 		})
-		t.Run("item exists and is const", func(t *testing.T) {
-			v := ic.SpawnVM()
-			v.LoadScript(cs.NEF.Script)
-			v.GasLimit = -1
-			v.Estack().PushVal(1)
-			v.Estack().PushVal("value")
-			v.Estack().PushVal("key")
-			require.NoError(t, storageGetContext(ic))
-			require.NoError(t, storagePutEx(ic))
-
-			v.Estack().PushVal("new")
-			v.Estack().PushVal("key")
-			require.NoError(t, storageGetContext(ic))
-			require.Error(t, storagePut(ic))
-		})
 	})
 }
 
@@ -301,16 +286,14 @@ func TestStorageDelete(t *testing.T) {
 	require.NoError(t, bc.contracts.Management.PutContractState(ic.DAO, cs))
 	v.LoadScriptWithHash(cs.NEF.Script, cs.Hash, callflag.All)
 	put := func(key, value string, flag int) {
-		v.Estack().PushVal(flag)
 		v.Estack().PushVal(value)
 		v.Estack().PushVal(key)
 		require.NoError(t, storageGetContext(ic))
-		require.NoError(t, storagePutEx(ic))
+		require.NoError(t, storagePut(ic))
 	}
 	put("key1", "value1", 0)
 	put("key2", "value2", 0)
 	put("key3", "value3", 0)
-	put("key4", "value4", 1)
 
 	t.Run("good", func(t *testing.T) {
 		v.Estack().PushVal("key1")
@@ -328,11 +311,6 @@ func TestStorageDelete(t *testing.T) {
 		require.NoError(t, storageContextAsReadOnly(ic))
 		require.Error(t, storageDelete(ic))
 	})
-	t.Run("constant item", func(t *testing.T) {
-		v.Estack().PushVal("key4")
-		require.NoError(t, storageGetContext(ic))
-		require.Error(t, storageDelete(ic))
-	})
 }
 
 // getTestContractState returns 2 contracts second of which is allowed to call the first.
diff --git a/pkg/core/interops.go b/pkg/core/interops.go
index 750a21ba5..9b961ccff 100644
--- a/pkg/core/interops.go
+++ b/pkg/core/interops.go
@@ -82,8 +82,6 @@ var systemInterops = []interop.Function{
 		RequiredFlags: callflag.ReadStates},
 	{Name: interopnames.SystemStoragePut, Func: storagePut, Price: 0, RequiredFlags: callflag.WriteStates,
 		ParamCount: 3}, // These don't have static price in C# code.
-	{Name: interopnames.SystemStoragePutEx, Func: storagePutEx, Price: 0, RequiredFlags: callflag.WriteStates,
-		ParamCount: 4},
 	{Name: interopnames.SystemStorageAsReadOnly, Func: storageContextAsReadOnly, Price: 1 << 4,
 		RequiredFlags: callflag.ReadStates, ParamCount: 1},
 }
diff --git a/pkg/core/interops_test.go b/pkg/core/interops_test.go
index 8f793bd5c..efed8f7cd 100644
--- a/pkg/core/interops_test.go
+++ b/pkg/core/interops_test.go
@@ -39,7 +39,6 @@ func TestUnexpectedNonInterops(t *testing.T) {
 		storageFind,
 		storageGet,
 		storagePut,
-		storagePutEx,
 	}
 	for _, f := range funcs {
 		for k, v := range vals {
diff --git a/pkg/core/native/native_neo.go b/pkg/core/native/native_neo.go
index 24ec29dd9..54f74fd70 100644
--- a/pkg/core/native/native_neo.go
+++ b/pkg/core/native/native_neo.go
@@ -926,9 +926,6 @@ func (n *NEO) putGASRecord(dao dao.DAO, index uint32, value *big.Int) error {
 	key := make([]byte, 5)
 	key[0] = prefixGASPerBlock
 	binary.BigEndian.PutUint32(key[1:], index)
-	si := &state.StorageItem{
-		Value:   bigint.ToBytes(value),
-		IsConst: false,
-	}
+	si := &state.StorageItem{Value: bigint.ToBytes(value)}
 	return dao.PutStorageItem(n.ID, key, si)
 }
diff --git a/pkg/core/state/storage_item.go b/pkg/core/state/storage_item.go
index 95f1f1c6c..d0427e180 100644
--- a/pkg/core/state/storage_item.go
+++ b/pkg/core/state/storage_item.go
@@ -6,18 +6,15 @@ import (
 
 // StorageItem is the value to be stored with read-only flag.
 type StorageItem struct {
-	Value   []byte
-	IsConst bool
+	Value []byte
 }
 
 // EncodeBinary implements Serializable interface.
 func (si *StorageItem) EncodeBinary(w *io.BinWriter) {
 	w.WriteVarBytes(si.Value)
-	w.WriteBool(si.IsConst)
 }
 
 // DecodeBinary implements Serializable interface.
 func (si *StorageItem) DecodeBinary(r *io.BinReader) {
 	si.Value = r.ReadVarBytes()
-	si.IsConst = r.ReadBool()
 }
diff --git a/pkg/core/state/storage_item_test.go b/pkg/core/state/storage_item_test.go
index 0da9c2a31..86540ce06 100644
--- a/pkg/core/state/storage_item_test.go
+++ b/pkg/core/state/storage_item_test.go
@@ -8,8 +8,7 @@ import (
 
 func TestEncodeDecodeStorageItem(t *testing.T) {
 	storageItem := &StorageItem{
-		Value:   []byte{},
-		IsConst: false,
+		Value: []byte{1, 2, 3},
 	}
 
 	testserdes.EncodeDecodeBinary(t, storageItem, new(StorageItem))
diff --git a/pkg/interop/storage/storage.go b/pkg/interop/storage/storage.go
index c9775ebfa..08392de20 100644
--- a/pkg/interop/storage/storage.go
+++ b/pkg/interop/storage/storage.go
@@ -38,16 +38,6 @@ const (
 	PickField1 FindFlags = 1 << 5
 )
 
-// PutFlags represents flag of `PutEx` syscall.
-type PutFlags byte
-
-const (
-	// PutDefault is a storage flag for non-constant items.
-	PutDefault PutFlags = 0
-	// PutConstant is a storage flag for constant items.
-	PutConstant PutFlags = 0x01
-)
-
 // ConvertContextToReadOnly returns new context from the given one, but with
 // writing capability turned off, so that you could only invoke Get and Find
 // using this new Context. If Context is already read-only this function is a
@@ -79,15 +69,6 @@ func Put(ctx Context, key interface{}, value interface{}) {
 	neogointernal.Syscall3NoReturn("System.Storage.Put", ctx, key, value)
 }
 
-// PutEx is an advanced version of Put which saves given value with given key
-// and given ReadOnly flag in the storage using given Context. `flag` argument
-// can either be odd for constant storage items or even for variable storage items.
-// Refer to Put function description for details on how to pass the remaining
-// arguments. This function uses `System.Storage.PutEx` syscall.
-func PutEx(ctx Context, key interface{}, value interface{}, flag PutFlags) {
-	neogointernal.Syscall4NoReturn("System.Storage.PutEx", ctx, key, value, flag)
-}
-
 // Get retrieves value stored for the given key using given Context. See Put
 // documentation on possible key and value types. If the value is not present in
 // the database it returns nil. This function uses `System.Storage.Get` syscall.