diff --git a/besu/src/main/java/org/hyperledger/besu/controller/IbftLegacyBesuControllerBuilder.java b/besu/src/main/java/org/hyperledger/besu/controller/IbftLegacyBesuControllerBuilder.java
index 944e96e288..51c917be77 100644
--- a/besu/src/main/java/org/hyperledger/besu/controller/IbftLegacyBesuControllerBuilder.java
+++ b/besu/src/main/java/org/hyperledger/besu/controller/IbftLegacyBesuControllerBuilder.java
@@ -23,8 +23,8 @@ import org.hyperledger.besu.consensus.common.VoteTallyUpdater;
 import org.hyperledger.besu.consensus.common.bft.BftContext;
 import org.hyperledger.besu.consensus.ibftlegacy.IbftLegacyBlockInterface;
 import org.hyperledger.besu.consensus.ibftlegacy.IbftProtocolSchedule;
-import org.hyperledger.besu.consensus.ibftlegacy.protocol.Istanbul64Protocol;
-import org.hyperledger.besu.consensus.ibftlegacy.protocol.Istanbul64ProtocolManager;
+import org.hyperledger.besu.consensus.ibftlegacy.protocol.Istanbul99Protocol;
+import org.hyperledger.besu.consensus.ibftlegacy.protocol.Istanbul99ProtocolManager;
 import org.hyperledger.besu.ethereum.ProtocolContext;
 import org.hyperledger.besu.ethereum.blockcreation.MiningCoordinator;
 import org.hyperledger.besu.ethereum.blockcreation.NoopMiningCoordinator;
@@ -58,7 +58,7 @@ public class IbftLegacyBesuControllerBuilder extends BesuControllerBuilder {
   protected SubProtocolConfiguration createSubProtocolConfiguration(
       final EthProtocolManager ethProtocolManager) {
     return new SubProtocolConfiguration()
-        .withSubProtocol(Istanbul64Protocol.get(), ethProtocolManager);
+        .withSubProtocol(Istanbul99Protocol.get(), ethProtocolManager);
   }
 
   @Override
@@ -113,7 +113,7 @@ public class IbftLegacyBesuControllerBuilder extends BesuControllerBuilder {
 
   @Override
   protected String getSupportedProtocol() {
-    return Istanbul64Protocol.get().getName();
+    return Istanbul99Protocol.get().getName();
   }
 
   @Override
@@ -128,7 +128,7 @@ public class IbftLegacyBesuControllerBuilder extends BesuControllerBuilder {
       final EthScheduler scheduler,
       final List<PeerValidator> peerValidators) {
     LOG.info("Operating on IBFT-1.0 network.");
-    return new Istanbul64ProtocolManager(
+    return new Istanbul99ProtocolManager(
         protocolContext.getBlockchain(),
         networkId,
         protocolContext.getWorldStateArchive(),
diff --git a/consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul64Protocol.java b/consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul99Protocol.java
similarity index 91%
rename from consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul64Protocol.java
rename to consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul99Protocol.java
index 2924b8fa51..5ace5a8eb2 100644
--- a/consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul64Protocol.java
+++ b/consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul99Protocol.java
@@ -24,19 +24,19 @@ import java.util.Arrays;
 import java.util.List;
 
 /**
- * Represents the istanbul/64 protocol as used by Quorum (effectively an extension of eth/63, which
+ * Represents the istanbul/64 protocol as used by Quorum (effectively an extension of eth/65, which
  * adds a single message type (0x11) to encapsulate all communications required for IBFT block
  * mining.
  */
-public class Istanbul64Protocol implements SubProtocol {
+public class Istanbul99Protocol implements SubProtocol {
 
   private static final String NAME = "istanbul";
-  private static final int VERSION = 64;
+  private static final int VERSION = 99;
 
-  static final Capability ISTANBUL64 = Capability.create(NAME, 64);
+  static final Capability ISTANBUL99 = Capability.create(NAME, 99);
   static final int INSTANBUL_MSG = 0x11;
 
-  private static final Istanbul64Protocol INSTANCE = new Istanbul64Protocol();
+  private static final Istanbul99Protocol INSTANCE = new Istanbul99Protocol();
 
   private static final List<Integer> istanbul64Messages =
       Arrays.asList(
@@ -115,7 +115,7 @@ public class Istanbul64Protocol implements SubProtocol {
     }
   }
 
-  public static Istanbul64Protocol get() {
+  public static Istanbul99Protocol get() {
     return INSTANCE;
   }
 }
diff --git a/consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul64ProtocolManager.java b/consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul99ProtocolManager.java
similarity index 92%
rename from consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul64ProtocolManager.java
rename to consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul99ProtocolManager.java
index 369563d3d9..bf0a7a1799 100644
--- a/consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul64ProtocolManager.java
+++ b/consensus/ibftlegacy/src/main/java/org/hyperledger/besu/consensus/ibftlegacy/protocol/Istanbul99ProtocolManager.java
@@ -32,9 +32,9 @@ import java.math.BigInteger;
 import java.util.List;
 
 /** This allows for interoperability with Quorum, but shouldn't be used otherwise. */
-public class Istanbul64ProtocolManager extends EthProtocolManager {
+public class Istanbul99ProtocolManager extends EthProtocolManager {
 
-  public Istanbul64ProtocolManager(
+  public Istanbul99ProtocolManager(
       final Blockchain blockchain,
       final BigInteger networkId,
       final WorldStateArchive worldStateArchive,
@@ -62,11 +62,11 @@ public class Istanbul64ProtocolManager extends EthProtocolManager {
 
   @Override
   public List<Capability> getSupportedCapabilities() {
-    return singletonList(Istanbul64Protocol.ISTANBUL64);
+    return singletonList(Istanbul99Protocol.ISTANBUL99);
   }
 
   @Override
   public String getSupportedProtocol() {
-    return Istanbul64Protocol.get().getName();
+    return Istanbul99Protocol.get().getName();
   }
 }