diff --git a/ruby/ext/google/protobuf_c/ruby-upb.c b/ruby/ext/google/protobuf_c/ruby-upb.c
index 9578e8e..1483124 100644
--- a/ruby/ext/google/protobuf_c/ruby-upb.c
+++ b/ruby/ext/google/protobuf_c/ruby-upb.c
@@ -404,7 +404,8 @@
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #include <stddef.h>
 
diff --git a/ruby/ext/google/protobuf_c/ruby-upb.h b/ruby/ext/google/protobuf_c/ruby-upb.h
index eebfde8..277b52b 100755
--- a/ruby/ext/google/protobuf_c/ruby-upb.h
+++ b/ruby/ext/google/protobuf_c/ruby-upb.h
@@ -4407,7 +4407,8 @@
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_MINITABLE_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_MINITABLE_H_
@@ -4911,7 +4912,8 @@
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_