diff --git a/flow/flat_buffers.cpp b/flow/flat_buffers.cpp
index 1cb4b1099d..89fb058f98 100644
--- a/flow/flat_buffers.cpp
+++ b/flow/flat_buffers.cpp
@@ -488,6 +488,10 @@ TEST_CASE("/flow/FlatBuffers/Standalone") {
 // Meant to be run with valgrind or asan, to catch heap buffer overflows
 TEST_CASE("/flow/FlatBuffers/Void") {
 	Standalone<StringRef> msg = ObjectWriter::toValue(Void(), Unversioned());
+	// Manually verified to be a valid flatbuffers message. This is technically brittle since there are other valid
+	// encodings of this message, but our implementation is unlikely to change.
+	ASSERT(msg == LiteralStringRef("\x14\x00\x00\x00J\xad\x1e\x00\x00\x00\x04\x00\x04\x00\x06\x00\x08\x00\x04\x00\x06"
+	                               "\x00\x00\x00\x04\x00\x00\x00\x12\x00\x00\x00"));
 	auto buffer = std::make_unique<uint8_t[]>(msg.size()); // Make a heap allocation of precisely the right size, so
 	                                                       // that asan or valgrind will catch any overflows
 	memcpy(buffer.get(), msg.begin(), msg.size());