diff --git a/flow/flat_buffers.cpp b/flow/flat_buffers.cpp
index a840dfc81e..679c3c8a61 100644
--- a/flow/flat_buffers.cpp
+++ b/flow/flat_buffers.cpp
@@ -452,6 +452,10 @@ TEST_CASE("/flow/FlatBuffers/VectorRef") {
 			serializedVector = StringRef(readerArena, writer.toStringRef());
 		}
 		ArenaObjectReader reader(readerArena, serializedVector, Unversioned());
+		// The VectorRef and Arena arguments are intentionally in a different order from the serialize call above.
+		// Arenas need to get serialized after any Ref types whose memory they own. In order for schema evolution to be
+		// possible, it needs to be okay to reorder an Arena so that it appears after a newly added Ref type. For this
+		// reason, Arenas are ignored by the wire protocol entirely. We test that behavior here.
 		reader.deserialize(FileIdentifierFor<decltype(outVec)>::value, outVec, vecArena);
 	}
 	ASSERT(src.size() == outVec.size());