diff --git a/src/hardforks/chainstart.json b/src/hardforks/chainstart.json
index e1d25a7..d907aad 100644
--- a/src/hardforks/chainstart.json
+++ b/src/hardforks/chainstart.json
@@ -17,6 +17,10 @@
     }
   },
   "gasPrices": {
+    "base": {
+      "v": 2,
+      "d": "Gas base cost, used e.g. for ChainID opcode (Istanbul)"
+    },
     "tierStep": {
       "v": [0, 2, 3, 5, 8, 10, 20],
       "d": "Once per operation, for a selection of them"
diff --git a/src/hardforks/istanbul.json b/src/hardforks/istanbul.json
index 4aed73d..7220e2a 100644
--- a/src/hardforks/istanbul.json
+++ b/src/hardforks/istanbul.json
@@ -7,6 +7,10 @@
   },
   "gasConfig": {},
   "gasPrices": {
+    "blake2bRound": {
+      "v": 1,
+      "d": "Gas cost per round for the Blake2b F precompile"
+    },
     "ecAdd": {
       "v": 150,
       "d": "Gas costs for curve addition precompile"
@@ -22,6 +26,10 @@
     "ecPairingWord": {
       "v": 34000,
       "d": "Gas costs regarding curve pairing precompile input length"
+    },
+    "txDataNonZero": {
+      "v": 16,
+      "d": "Per byte of data attached to a transaction that is not equal to zero. NOTE: Not payable on data of calls between transactions"
     }
   },
   "vm": {},