diff --git a/ethereumj-core/src/main/java/org/ethereum/config/BlockchainConfig.java b/ethereumj-core/src/main/java/org/ethereum/config/BlockchainConfig.java
index 431d56a379..c889d08dab 100644
--- a/ethereumj-core/src/main/java/org/ethereum/config/BlockchainConfig.java
+++ b/ethereumj-core/src/main/java/org/ethereum/config/BlockchainConfig.java
@@ -52,6 +52,11 @@ public interface BlockchainConfig {
      */
     BigInteger calcDifficulty(BlockHeader curBlock, BlockHeader parent);
 
+    /**
+     * Calculates difficulty adjustment to target mean block time
+     */
+    BigInteger getCalcDifficultyMultiplier(BlockHeader curBlock, BlockHeader parent);
+
     /**
      * Calculates transaction gas fee
      */
diff --git a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/AbstractConfig.java b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/AbstractConfig.java
index 0d5a562a7b..ad9eba8a90 100644
--- a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/AbstractConfig.java
+++ b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/AbstractConfig.java
@@ -100,8 +100,6 @@ public BigInteger calcDifficulty(BlockHeader curBlock, BlockHeader parent) {
         return difficulty;
     }
 
-    protected abstract BigInteger getCalcDifficultyMultiplier(BlockHeader curBlock, BlockHeader parent);
-
     protected int getExplosion(BlockHeader curBlock, BlockHeader parent) {
         int periodCount = (int) (curBlock.getNumber() / getConstants().getEXP_DIFFICULTY_PERIOD());
         return periodCount - 2;
diff --git a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/ByzantiumConfig.java b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/ByzantiumConfig.java
new file mode 100644
index 0000000000..3dcb50eda9
--- /dev/null
+++ b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/ByzantiumConfig.java
@@ -0,0 +1,39 @@
+package org.ethereum.config.blockchain;
+
+import org.ethereum.config.BlockchainConfig;
+import org.ethereum.config.Constants;
+import org.ethereum.core.Block;
+import org.ethereum.core.BlockHeader;
+import org.ethereum.core.Repository;
+import org.spongycastle.util.encoders.Hex;
+
+import java.math.BigInteger;
+
+/**
+ * EIPs included in the Hard Fork:
+ * <ul>
+ *     <li>100 - Change difficulty adjustment to target mean block time including uncles</li>
+ *     <li>140 - REVERT instruction in the Ethereum Virtual Machine</li>
+ *     <li>196 - Precompiled contracts for addition and scalar multiplication on the elliptic curve alt_bn128</li>
+ *     <li>197 - Precompiled contracts for optimal Ate pairing check on the elliptic curve alt_bn128</li>
+ *     <li>198 - Precompiled contract for bigint modular exponentiation</li>
+ *     <li>211 - New opcodes: RETURNDATASIZE and RETURNDATACOPY</li>
+ *     <li>214 - New opcode STATICCALL</li>
+ *     <li>658 - Embedding transaction return data in receipts</li>
+ * </ul>
+ *
+ * @author Mikhail Kalinin
+ * @since 14.08.2017
+ */
+public class ByzantiumConfig extends Eip160HFConfig {
+
+    public ByzantiumConfig(BlockchainConfig parent) {
+        super(parent);
+    }
+
+    @Override
+    public BigInteger getCalcDifficultyMultiplier(BlockHeader curBlock, BlockHeader parent) {
+        long unclesAdj = parent.hasUncles() ? 2 : 1;
+        return BigInteger.valueOf(Math.max(unclesAdj - (curBlock.getTimestamp() - parent.getTimestamp()) / 9, -99));
+    }
+}
diff --git a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/ETCFork3M.java b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/ETCFork3M.java
index 82b8b834e1..77f4a18dd9 100644
--- a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/ETCFork3M.java
+++ b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/ETCFork3M.java
@@ -66,7 +66,8 @@ public BigInteger calcDifficulty(BlockHeader curBlock, BlockHeader parent) {
         return difficulty;
     }
 
-    protected BigInteger getCalcDifficultyMultiplier(BlockHeader curBlock, BlockHeader parent) {
+    @Override
+    public BigInteger getCalcDifficultyMultiplier(BlockHeader curBlock, BlockHeader parent) {
         return BigInteger.valueOf(Math.max(1 - (curBlock.getTimestamp() - parent.getTimestamp()) / 10, -99));
     }
 
diff --git a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/Eip150HFConfig.java b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/Eip150HFConfig.java
index 7e5d1354f2..7e963ff137 100644
--- a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/Eip150HFConfig.java
+++ b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/Eip150HFConfig.java
@@ -87,6 +87,11 @@ public BigInteger calcDifficulty(BlockHeader curBlock, BlockHeader parent) {
         return this.parent.calcDifficulty(curBlock, parent);
     }
 
+    @Override
+    public BigInteger getCalcDifficultyMultiplier(BlockHeader curBlock, BlockHeader parent) {
+        return this.parent.getCalcDifficultyMultiplier(curBlock, parent);
+    }
+
     @Override
     public long getTransactionCost(Transaction tx) {
         return parent.getTransactionCost(tx);
diff --git a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/HomesteadConfig.java b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/HomesteadConfig.java
index 45a63f3047..9bfd4648cf 100644
--- a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/HomesteadConfig.java
+++ b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/HomesteadConfig.java
@@ -52,7 +52,7 @@ public HomesteadConfig(Constants constants) {
     }
 
     @Override
-    protected BigInteger getCalcDifficultyMultiplier(BlockHeader curBlock, BlockHeader parent) {
+    public BigInteger getCalcDifficultyMultiplier(BlockHeader curBlock, BlockHeader parent) {
         return BigInteger.valueOf(Math.max(1 - (curBlock.getTimestamp() - parent.getTimestamp()) / 10, -99));
     }
 
diff --git a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/OlympicConfig.java b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/OlympicConfig.java
index fd3bb40f93..82f8d8eb97 100644
--- a/ethereumj-core/src/main/java/org/ethereum/config/blockchain/OlympicConfig.java
+++ b/ethereumj-core/src/main/java/org/ethereum/config/blockchain/OlympicConfig.java
@@ -37,7 +37,7 @@ public OlympicConfig(Constants constants) {
     }
 
     @Override
-    protected BigInteger getCalcDifficultyMultiplier(BlockHeader curBlock, BlockHeader parent) {
+    public BigInteger getCalcDifficultyMultiplier(BlockHeader curBlock, BlockHeader parent) {
         return BigInteger.valueOf(curBlock.getTimestamp() >= parent.getTimestamp() +
                 getConstants().getDURATION_LIMIT() ? -1 : 1);
     }
diff --git a/ethereumj-core/src/main/java/org/ethereum/core/BlockHeader.java b/ethereumj-core/src/main/java/org/ethereum/core/BlockHeader.java
index 125d016a7d..976393c17f 100644
--- a/ethereumj-core/src/main/java/org/ethereum/core/BlockHeader.java
+++ b/ethereumj-core/src/main/java/org/ethereum/core/BlockHeader.java
@@ -148,7 +148,7 @@ public BlockHeader(byte[] parentHash, byte[] unclesHash, byte[] coinbase,
         this.extraData = extraData;
         this.mixHash = mixHash;
         this.nonce = nonce;
-        this.stateRoot = HashUtil.EMPTY_TRIE_HASH;
+        this.stateRoot = EMPTY_TRIE_HASH;
     }
 
     public boolean isGenesis() {
@@ -374,6 +374,10 @@ public BigInteger calcDifficulty(BlockchainNetConfig config, BlockHeader parent)
                 calcDifficulty(this, parent);
     }
 
+    public boolean hasUncles() {
+        return !FastByteComparisons.equal(unclesHash, EMPTY_TRIE_HASH);
+    }
+
     public String toString() {
         return toStringWithSuffix("\n");
     }