diff --git a/internal/testchain/transaction.go b/internal/testchain/transaction.go
index e4400e74e..2efcb70ad 100644
--- a/internal/testchain/transaction.go
+++ b/internal/testchain/transaction.go
@@ -91,17 +91,27 @@ func NewDeployTx(bc blockchainer.Blockchainer, name string, sender util.Uint160,
 
 // SignTx signs provided transactions with validator keys.
 func SignTx(bc blockchainer.Blockchainer, txs ...*transaction.Transaction) error {
+	signTxGeneric(bc, Sign, ownerScript, txs...)
+	return nil
+}
+
+// SignTxCommittee signs transactions by committee.
+func SignTxCommittee(bc blockchainer.Blockchainer, txs ...*transaction.Transaction) error {
+	signTxGeneric(bc, SignCommittee, CommitteeVerificationScript(), txs...)
+	return nil
+}
+
+func signTxGeneric(bc blockchainer.Blockchainer, sign func([]byte) []byte, verif []byte, txs ...*transaction.Transaction) {
 	for _, tx := range txs {
 		size := io.GetVarSize(tx)
-		netFee, sizeDelta := fee.Calculate(bc.GetPolicer().GetBaseExecFee(), ownerScript)
+		netFee, sizeDelta := fee.Calculate(bc.GetPolicer().GetBaseExecFee(), verif)
 		tx.NetworkFee += netFee
 		size += sizeDelta
 		tx.NetworkFee += int64(size) * bc.FeePerByte()
 		data := tx.GetSignedPart()
 		tx.Scripts = []transaction.Witness{{
-			InvocationScript:   Sign(data),
-			VerificationScript: ownerScript,
+			InvocationScript:   sign(data),
+			VerificationScript: verif,
 		}}
 	}
-	return nil
 }
diff --git a/pkg/core/blockchain_test.go b/pkg/core/blockchain_test.go
index 7325529d7..5183a5a2d 100644
--- a/pkg/core/blockchain_test.go
+++ b/pkg/core/blockchain_test.go
@@ -139,7 +139,7 @@ func TestAddBlockStateRoot(t *testing.T) {
 
 	tx := newNEP17Transfer(bc.contracts.NEO.Hash, neoOwner, util.Uint160{}, 1)
 	tx.ValidUntilBlock = bc.BlockHeight() + 1
-	addSigners(tx)
+	addSigners(neoOwner, tx)
 	require.NoError(t, testchain.SignTx(bc, tx))
 
 	lastBlock := bc.topBlock.Load().(*block.Block)
@@ -198,7 +198,7 @@ func TestGetHeader(t *testing.T) {
 	bc := newTestChain(t)
 	tx := transaction.New(netmode.UnitTestNet, []byte{byte(opcode.PUSH1)}, 0)
 	tx.ValidUntilBlock = bc.BlockHeight() + 1
-	addSigners(tx)
+	addSigners(neoOwner, tx)
 	assert.Nil(t, testchain.SignTx(bc, tx))
 	block := bc.newBlock(tx)
 	err := bc.AddBlock(block)
@@ -1176,7 +1176,7 @@ func TestIsTxStillRelevant(t *testing.T) {
 		txDeploy, h, err := testchain.NewDeployTx(bc, "TestVerify", neoOwner, strings.NewReader(src))
 		require.NoError(t, err)
 		txDeploy.ValidUntilBlock = bc.BlockHeight() + 1
-		addSigners(txDeploy)
+		addSigners(neoOwner, txDeploy)
 		require.NoError(t, testchain.SignTx(bc, txDeploy))
 		require.NoError(t, bc.AddBlock(bc.newBlock(txDeploy)))
 
diff --git a/pkg/core/helper_test.go b/pkg/core/helper_test.go
index 9cb78bb74..cff9c3274 100644
--- a/pkg/core/helper_test.go
+++ b/pkg/core/helper_test.go
@@ -400,10 +400,10 @@ func newDeployTx(t *testing.T, bc *Blockchain, sender util.Uint160, name, ctrNam
 	return tx, h
 }
 
-func addSigners(txs ...*transaction.Transaction) {
+func addSigners(sender util.Uint160, txs ...*transaction.Transaction) {
 	for _, tx := range txs {
 		tx.Signers = []transaction.Signer{{
-			Account:          neoOwner,
+			Account:          sender,
 			Scopes:           transaction.CalledByEntry,
 			AllowedContracts: nil,
 			AllowedGroups:    nil,
@@ -428,8 +428,8 @@ func addNetworkFee(bc *Blockchain, tx *transaction.Transaction, sender *wallet.A
 	return nil
 }
 
-func prepareContractMethodInvoke(chain *Blockchain, sysfee int64,
-	hash util.Uint160, method string, args ...interface{}) (*transaction.Transaction, error) {
+func prepareContractMethodInvokeGeneric(chain *Blockchain, sysfee int64,
+	hash util.Uint160, method string, isCommittee bool, args ...interface{}) (*transaction.Transaction, error) {
 	w := io.NewBufBinWriter()
 	emit.AppCall(w.BinWriter, hash, method, callflag.All, args...)
 	if w.Err != nil {
@@ -438,14 +438,26 @@ func prepareContractMethodInvoke(chain *Blockchain, sysfee int64,
 	script := w.Bytes()
 	tx := transaction.New(chain.GetConfig().Magic, script, sysfee)
 	tx.ValidUntilBlock = chain.blockHeight + 1
-	addSigners(tx)
-	err := testchain.SignTx(chain, tx)
+	var err error
+	if isCommittee {
+		addSigners(testchain.CommitteeScriptHash(), tx)
+		err = testchain.SignTxCommittee(chain, tx)
+	} else {
+		addSigners(neoOwner, tx)
+		err = testchain.SignTx(chain, tx)
+	}
 	if err != nil {
 		return nil, err
 	}
 	return tx, nil
 }
 
+func prepareContractMethodInvoke(chain *Blockchain, sysfee int64,
+	hash util.Uint160, method string, args ...interface{}) (*transaction.Transaction, error) {
+	return prepareContractMethodInvokeGeneric(chain, sysfee, hash,
+		method, false, args...)
+}
+
 func persistBlock(chain *Blockchain, txs ...*transaction.Transaction) ([]*state.AppExecResult, error) {
 	b := chain.newBlock(txs...)
 	err := chain.AddBlock(b)
@@ -465,7 +477,13 @@ func persistBlock(chain *Blockchain, txs ...*transaction.Transaction) ([]*state.
 }
 
 func invokeContractMethod(chain *Blockchain, sysfee int64, hash util.Uint160, method string, args ...interface{}) (*state.AppExecResult, error) {
-	tx, err := prepareContractMethodInvoke(chain, sysfee, hash, method, args...)
+	return invokeContractMethodGeneric(chain, sysfee, hash, method, false, args...)
+}
+
+func invokeContractMethodGeneric(chain *Blockchain, sysfee int64, hash util.Uint160, method string,
+	isCommittee bool, args ...interface{}) (*state.AppExecResult, error) {
+	tx, err := prepareContractMethodInvokeGeneric(chain, sysfee, hash,
+		method, isCommittee, args...)
 	if err != nil {
 		return nil, err
 	}
@@ -512,7 +530,7 @@ func transferTokenFromMultisigAccount(t *testing.T, chain *Blockchain, to, token
 	transferTx := newNEP17Transfer(tokenHash, testchain.MultisigScriptHash(), to, amount, additionalArgs...)
 	transferTx.SystemFee = 100000000
 	transferTx.ValidUntilBlock = chain.BlockHeight() + 1
-	addSigners(transferTx)
+	addSigners(neoOwner, transferTx)
 	require.NoError(t, testchain.SignTx(chain, transferTx))
 	b := chain.newBlock(transferTx)
 	require.NoError(t, chain.AddBlock(b))