diff --git a/internal/testprotos/messageset/messagesetpb/message_set.pb.go b/internal/testprotos/messageset/messagesetpb/message_set.pb.go
index 71dea75..f6d756e 100644
--- a/internal/testprotos/messageset/messagesetpb/message_set.pb.go
+++ b/internal/testprotos/messageset/messagesetpb/message_set.pb.go
@@ -104,19 +104,20 @@
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 }
 
 var (
diff --git a/internal/testprotos/messageset/messagesetpb/message_set.proto b/internal/testprotos/messageset/messagesetpb/message_set.proto
index f16a5cb..46b7601 100644
--- a/internal/testprotos/messageset/messagesetpb/message_set.proto
+++ b/internal/testprotos/messageset/messagesetpb/message_set.proto
@@ -11,7 +11,13 @@
 message MessageSet {
   option message_set_wire_format = true;
 
-  extensions 4 to max;
+  extensions 4 to 529999999;
+  extensions 530000000 to max
+  [declaration = {
+    number: 536870912
+    full_name: ".goproto.proto.messageset.ExtLargeNumber.message_set_extension"
+    type: ".goproto.proto.messageset.ExtLargeNumber"
+  }];
 }
 
 message MessageSetContainer {