diff --git a/src/test/transaction_tests.cpp b/src/test/transaction_tests.cpp
--- a/src/test/transaction_tests.cpp
+++ b/src/test/transaction_tests.cpp
@@ -801,6 +801,19 @@
     reason.clear();
     BOOST_CHECK(!IsStandardTx(CTransaction(t), reason));
     BOOST_CHECK_EQUAL(reason, "multi-op-return");
+
+    // Check large scriptSig (non-standard if size is >1650 bytes)
+    t.vout.resize(1);
+    t.vout[0].nValue = MAX_MONEY;
+    t.vout[0].scriptPubKey = GetScriptForDestination(PKHash(key.GetPubKey()));
+    // OP_PUSHDATA2 with len (3 bytes) + data (1647 bytes) = 1650 bytes
+    t.vin[0].scriptSig = CScript() << std::vector<uint8_t>(1647, 0); // 1650
+    BOOST_CHECK(IsStandardTx(CTransaction(t), reason));
+
+    t.vin[0].scriptSig = CScript() << std::vector<uint8_t>(1648, 0); // 1651
+    reason.clear();
+    BOOST_CHECK(!IsStandardTx(CTransaction(t), reason));
+    BOOST_CHECK_EQUAL(reason, "scriptsig-size");
 }
 
 BOOST_AUTO_TEST_CASE(txsize_activation_test) {