diff --git a/lib/flutter_libsparkmobile.dart b/lib/flutter_libsparkmobile.dart
index 304bee6e..2f20bb36 100644
--- a/lib/flutter_libsparkmobile.dart
+++ b/lib/flutter_libsparkmobile.dart
@@ -20,8 +20,8 @@ const kSparkBaseDerivationPath = "m/44'/136'/0'/$kSparkChain/";
 const kSparkBaseDerivationPathTestnet = "m/44'/1'/0'/$kSparkChain/";
 
 const kMaxNameLength =
-    20; // max 20 symbols, alphanumerical or "-_.", case-insensitive
-const kNameRegexString = r'^[a-zA-Z0-9\-_\.]+$';
+    20; // max 20 symbols, alphanumerical or "-.", case-insensitive
+const kNameRegexString = r'^[a-zA-Z0-9.-]+$';
 const kMaxAdditionalInfoLengthBytes = 1024;
 const kMaxNameRegistrationLengthYears = 10;
 const kStage3CommunityFundAddressMainNet = "aFA2TbqG9cnhhzX5Yny2pBJRK5EaEqLCH7";
diff --git a/src/deps/sparkmobile/src/sparkname.h b/src/deps/sparkmobile/src/sparkname.h
index 0d2805f8..a9a77716 100644
--- a/src/deps/sparkmobile/src/sparkname.h
+++ b/src/deps/sparkmobile/src/sparkname.h
@@ -9,7 +9,7 @@ namespace spark {
 struct CSparkNameTxData
 {
 public:
-    static const uint16_t CURRENT_VERSION = 1;
+    static const uint16_t CURRENT_VERSION = 2;
 
 public:
     uint16_t nVersion{CURRENT_VERSION};     // version
@@ -27,6 +27,8 @@ struct CSparkNameTxData
     std::string additionalInfo;
     // failsafe if the hash of the transaction data is can't be converted to a scalar for proof creation/verification
     uint32_t hashFailsafe{0};
+    // Registration-only; add transfer fields if mobile starts creating Spark Name transfers.
+    uint8_t operationType{0};
 
     ADD_SERIALIZE_METHODS;
 
@@ -34,6 +36,8 @@ struct CSparkNameTxData
     void SerializationOp(Stream &s, Operation ser_action)
     {
         READWRITE(nVersion);
+        if (nVersion != 1 && nVersion != 2)
+            throw std::ios_base::failure("Unsupported Spark Name transaction data version");
         READWRITE(inputsHash);
         READWRITE(name);
         READWRITE(sparkAddress);
@@ -41,6 +45,10 @@ struct CSparkNameTxData
         READWRITE(sparkNameValidityBlocks);
         READWRITE(additionalInfo);
         READWRITE(hashFailsafe);
+        if (nVersion == 2)
+        {
+            READWRITE(operationType);
+        }
     }
 };
 
diff --git a/src/deps/sparkmobile/tests/spark_name_test.cpp b/src/deps/sparkmobile/tests/spark_name_test.cpp
index 018e70c0..302b909e 100644
--- a/src/deps/sparkmobile/tests/spark_name_test.cpp
+++ b/src/deps/sparkmobile/tests/spark_name_test.cpp
@@ -42,6 +42,8 @@ BOOST_AUTO_TEST_CASE(spark_names)
     BOOST_CHECK_EQUAL(decodedData.sparkAddress, sparkNameData.sparkAddress);
     BOOST_CHECK_EQUAL(decodedData.sparkNameValidityBlocks, sparkNameData.sparkNameValidityBlocks);
     BOOST_CHECK_EQUAL(decodedData.additionalInfo, sparkNameData.additionalInfo);
+    BOOST_CHECK_EQUAL(decodedData.nVersion, uint16_t{2});
+    BOOST_CHECK_EQUAL((int)decodedData.operationType, 0);
     BOOST_CHECK(!decodedData.addressOwnershipProof.empty());
 
     spark::OwnershipProof deserializedOwnershipProof;
@@ -54,4 +56,19 @@ BOOST_AUTO_TEST_CASE(spark_names)
     BOOST_CHECK(address.verify_own(m, deserializedOwnershipProof));
 }
 
+BOOST_AUTO_TEST_CASE(rejects_unsupported_spark_name_versions)
+{
+    spark::CSparkNameTxData data;
+    data.nVersion = 3;
+    CDataStream serialized(SER_NETWORK, PROTOCOL_VERSION);
+    BOOST_CHECK_THROW(serialized << data, std::ios_base::failure);
+
+    data.nVersion = 2;
+    CDataStream encodedData(SER_NETWORK, PROTOCOL_VERSION);
+    encodedData << data;
+    encodedData[0] = 3;
+    encodedData[1] = 0;
+    BOOST_CHECK_THROW(encodedData >> data, std::ios_base::failure);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
diff --git a/test/flutter_libsparkmobile_test.dart b/test/flutter_libsparkmobile_test.dart
index 66dc9255..c3938118 100644
--- a/test/flutter_libsparkmobile_test.dart
+++ b/test/flutter_libsparkmobile_test.dart
@@ -3,6 +3,12 @@ import 'package:flutter_libsparkmobile/src/extensions.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  test('Spark Names reject underscores', () {
+    final pattern = RegExp(kNameRegexString);
+    expect(pattern.hasMatch('NAME-FOR.TESTING'), isTrue);
+    expect(pattern.hasMatch('NAME_FOR_TESTING'), isFalse);
+  });
+
   test('mnemonic to address test', () async {
     // Generate key data from the mnemonic.
     //