diff --git a/pkg/network/server.go b/pkg/network/server.go
index 5a8f7027d..8f97665cd 100644
--- a/pkg/network/server.go
+++ b/pkg/network/server.go
@@ -1201,6 +1201,9 @@ func (s *Server) verifyNotaryRequest(_ *transaction.Transaction, data any) error
 	if r.FallbackTransaction.Sender() != notaryHash {
 		return fmt.Errorf("P2PNotary contract should be a sender of the fallback transaction, got %s", address.Uint160ToString(r.FallbackTransaction.Sender()))
 	}
+	if r.MainTransaction.Sender() == notaryHash {
+		return errors.New("P2PNotary contract is not allowed to be the sender of the main transaction")
+	}
 	depositExpiration := s.chain.GetNotaryDepositExpiration(payer)
 	if r.FallbackTransaction.ValidUntilBlock >= depositExpiration {
 		return fmt.Errorf("fallback transaction is valid after deposit is unlocked: ValidUntilBlock is %d, deposit lock for %s expires at %d", r.FallbackTransaction.ValidUntilBlock, address.Uint160ToString(payer), depositExpiration)
diff --git a/pkg/network/server_test.go b/pkg/network/server_test.go
index 71849a82f..1f862d105 100644
--- a/pkg/network/server_test.go
+++ b/pkg/network/server_test.go
@@ -1036,7 +1036,10 @@ func TestVerifyNotaryRequest(t *testing.T) {
 	require.NoError(t, err)
 	newNotaryRequest := func() *payload.P2PNotaryRequest {
 		return &payload.P2PNotaryRequest{
-			MainTransaction: &transaction.Transaction{Script: []byte{0, 1, 2}},
+			MainTransaction: &transaction.Transaction{
+				Script:  []byte{0, 1, 2},
+				Signers: []transaction.Signer{{Account: random.Uint160()}},
+			},
 			FallbackTransaction: &transaction.Transaction{
 				ValidUntilBlock: 321,
 				Signers:         []transaction.Signer{{Account: bc.NotaryContractScriptHash}, {Account: random.Uint160()}},
@@ -1057,6 +1060,13 @@ func TestVerifyNotaryRequest(t *testing.T) {
 		require.Error(t, s.verifyNotaryRequest(nil, r))
 	})
 
+	t.Run("bad main sender", func(t *testing.T) {
+		bc.VerifyWitnessF = func() (int64, error) { return 0, nil }
+		r := newNotaryRequest()
+		r.MainTransaction.Signers[0] = transaction.Signer{Account: bc.NotaryContractScriptHash}
+		require.Error(t, s.verifyNotaryRequest(nil, r))
+	})
+
 	t.Run("expired deposit", func(t *testing.T) {
 		r := newNotaryRequest()
 		bc.NotaryDepositExpiration = r.FallbackTransaction.ValidUntilBlock