diff --git a/sdk-core/src/main/java/dev/restate/sdk/core/MessageHeader.java b/sdk-core/src/main/java/dev/restate/sdk/core/MessageHeader.java
index de6de0bd..96e00bf4 100644
--- a/sdk-core/src/main/java/dev/restate/sdk/core/MessageHeader.java
+++ b/sdk-core/src/main/java/dev/restate/sdk/core/MessageHeader.java
@@ -14,7 +14,7 @@
 
 public class MessageHeader {
 
-  static final short SUPPORTED_PROTOCOL_VERSION = 0;
+  static final short SUPPORTED_PROTOCOL_VERSION = 1;
 
   static final short VERSION_MASK = 0x03FF;
   static final short DONE_FLAG = 0x0001;
diff --git a/sdk-core/src/test/java/dev/restate/sdk/core/ProtoUtils.java b/sdk-core/src/test/java/dev/restate/sdk/core/ProtoUtils.java
index 6ad5cc21..54c51fc7 100644
--- a/sdk-core/src/test/java/dev/restate/sdk/core/ProtoUtils.java
+++ b/sdk-core/src/test/java/dev/restate/sdk/core/ProtoUtils.java
@@ -33,7 +33,10 @@ public class ProtoUtils {
    */
   public static MessageHeader headerFromMessage(MessageLite msg) {
     if (msg instanceof Protocol.StartMessage) {
-      return new MessageHeader(MessageType.StartMessage, (short) 0, msg.getSerializedSize());
+      return new MessageHeader(
+          MessageType.StartMessage,
+          MessageHeader.SUPPORTED_PROTOCOL_VERSION,
+          msg.getSerializedSize());
     } else if (msg instanceof Protocol.CompletionMessage) {
       return new MessageHeader(MessageType.CompletionMessage, (short) 0, msg.getSerializedSize());
     }