diff --git a/hadoop-common-project/hadoop-common/src/main/proto/ProtobufRpcEngine.proto b/hadoop-common-project/hadoop-common/src/main/proto/ProtobufRpcEngine.proto
index fa11313402..f72cf1a8da 100644
--- a/hadoop-common-project/hadoop-common/src/main/proto/ProtobufRpcEngine.proto
+++ b/hadoop-common-project/hadoop-common/src/main/proto/ProtobufRpcEngine.proto
@@ -64,4 +64,7 @@ message RequestHeaderProto {
   
   /** protocol version of class declaring the called method */
   required uint64 clientProtocolVersion = 3;
+
+  /** protocol extensions */
+  extensions 1000 to max;
 }
diff --git a/hadoop-common-project/hadoop-common/src/main/proto/ProtobufRpcEngine2.proto b/hadoop-common-project/hadoop-common/src/main/proto/ProtobufRpcEngine2.proto
index 16ee880e7b..c3023ec26d 100644
--- a/hadoop-common-project/hadoop-common/src/main/proto/ProtobufRpcEngine2.proto
+++ b/hadoop-common-project/hadoop-common/src/main/proto/ProtobufRpcEngine2.proto
@@ -64,4 +64,7 @@ message RequestHeaderProto {
 
   /** protocol version of class declaring the called method */
   required uint64 clientProtocolVersion = 3;
+
+  /** protocol extensions */
+  extensions 1000 to max;
 }