diff --git a/libethcore/EVMSchedule.h b/libethcore/EVMSchedule.h
index f70eddeaf5a..7f024da916e 100644
--- a/libethcore/EVMSchedule.h
+++ b/libethcore/EVMSchedule.h
@@ -150,6 +150,7 @@ static const EVMSchedule ConstantinopleFixSchedule = [] {
 static const EVMSchedule IstanbulSchedule = [] {
     EVMSchedule schedule = ConstantinopleFixSchedule;
     schedule.accountVersion = 1;
+    schedule.txDataNonZeroGas = 16;
     return schedule;
 }();
 
diff --git a/test/unittests/libethereum/Transaction.cpp b/test/unittests/libethereum/Transaction.cpp
index 95db73accfa..44b5c2c2c97 100644
--- a/test/unittests/libethereum/Transaction.cpp
+++ b/test/unittests/libethereum/Transaction.cpp
@@ -33,8 +33,10 @@ BOOST_FIXTURE_TEST_SUITE(libethereum, TestOutputHelperFixture)
 
 BOOST_AUTO_TEST_CASE(TransactionGasRequired)
 {
+    // Transactio data is 0358ac39584bc98a7c979f984b03, 14 bytes
     Transaction tr(fromHex("0xf86d800182521c94095e7baea6a6c7c4c2dfeb977efac326af552d870a8e0358ac39584bc98a7c979f984b031ba048b55bfa915ac795c431978d8a6a992b628d557da5ff759b307d495a36649353a0efffd310ac743f371de3b9f7f9cb56c0b28ad43601b4ab949f53faa07bd2c804"), CheckTransaction::None);
-    BOOST_CHECK_EQUAL(tr.baseGasRequired(FrontierSchedule), 21952);
+    BOOST_CHECK_EQUAL(tr.baseGasRequired(FrontierSchedule), 14 * 68 + 21000);
+    BOOST_CHECK_EQUAL(tr.baseGasRequired(IstanbulSchedule), 14 * 16 + 21000);
 }
 
 BOOST_AUTO_TEST_CASE(ExecutionResultOutput)