diff --git a/protobuf/src/main/java/io/grpc/protobuf/ProtoUtils.java b/protobuf/src/main/java/io/grpc/protobuf/ProtoUtils.java
index b541e2f820..68e03e1034 100644
--- a/protobuf/src/main/java/io/grpc/protobuf/ProtoUtils.java
+++ b/protobuf/src/main/java/io/grpc/protobuf/ProtoUtils.java
@@ -17,6 +17,7 @@
 package io.grpc.protobuf;
 
 import com.google.protobuf.Message;
+import io.grpc.ExperimentalApi;
 import io.grpc.Metadata;
 import io.grpc.MethodDescriptor.Marshaller;
 import io.grpc.protobuf.lite.ProtoLiteUtils;