diff --git a/protobuf/src/main/java/io/grpc/protobuf/ProtoUtils.java b/protobuf/src/main/java/io/grpc/protobuf/ProtoUtils.java
index 68e03e1034..21ea6f0201 100644
--- a/protobuf/src/main/java/io/grpc/protobuf/ProtoUtils.java
+++ b/protobuf/src/main/java/io/grpc/protobuf/ProtoUtils.java
@@ -43,6 +43,8 @@ public class ProtoUtils {
 
   /**
    * Produce a metadata marshaller for a protobuf type.
+   * 
+   * @since 1.13.0
    */
   @ExperimentalApi("https://github.com/grpc/grpc-java/issues/4477")
   public static <T extends Message> Metadata.BinaryMarshaller<T> metadataMarshaller(T instance) {