diff --git a/pkg/core/interop_neo_test.go b/pkg/core/interop_neo_test.go
index 2336fed8a..525b04942 100644
--- a/pkg/core/interop_neo_test.go
+++ b/pkg/core/interop_neo_test.go
@@ -210,7 +210,7 @@ func TestECDSAVerify(t *testing.T) {
 	t.Run("invalid public key", func(t *testing.T) {
 		sign := priv.Sign(msg)
 		pub := priv.PublicKey().Bytes()
-		pub = pub[10:]
+		pub[0] = 0xFF // invalid prefix
 		runCase(t, true, false, sign, pub, msg)
 	})
 }