diff --git a/source/network/NetClient.cpp b/source/network/NetClient.cpp
index 6c9da4adf8..878f098593 100644
--- a/source/network/NetClient.cpp
+++ b/source/network/NetClient.cpp
@@ -524,6 +524,9 @@ bool CNetClient::HandleMessage(CNetMessage* message)
 	{
 		CFileTransferRequestMessage* reqMessage = static_cast<CFileTransferRequestMessage*>(message);
 
+		ENSURE(static_cast<CNetFileTransferer::RequestType>(reqMessage->m_RequestType) ==
+			CNetFileTransferer::RequestType::REJOIN);
+
 		// TODO: we should support different transfer request types, instead of assuming
 		// it's always requesting the simulation state
 
@@ -786,7 +789,7 @@ bool CNetClient::OnJoinSyncStart(CNetClient* client, CFsmEvent* event)
 	CJoinSyncStartMessage* joinSyncStartMessage = (CJoinSyncStartMessage*)event->GetParamRef();
 
 	// The server wants us to start downloading the game state from it, so do so
-	client->m_Session->GetFileTransferer().StartTask(
+	client->m_Session->GetFileTransferer().StartTask(CNetFileTransferer::RequestType::REJOIN,
 		[client, initAttributes = std::move(joinSyncStartMessage->m_InitAttributes)](std::string buffer)
 			mutable
 		{
diff --git a/source/network/NetFileTransfer.cpp b/source/network/NetFileTransfer.cpp
index 8d668037e8..32e7fc4968 100644
--- a/source/network/NetFileTransfer.cpp
+++ b/source/network/NetFileTransfer.cpp
@@ -141,13 +141,14 @@ Status CNetFileTransferer::OnFileTransferAck(const CFileTransferAckMessage& mess
 
 }
 
-void CNetFileTransferer::StartTask(std::function<void(std::string)> task)
+void CNetFileTransferer::StartTask(RequestType requestType, std::function<void(std::string)> task)
 {
 	u32 requestID = m_NextRequestID++;
 
 	m_FileReceiveTasks.emplace(requestID, AsyncFileReceiveTask{std::move(task)});
 
 	CFileTransferRequestMessage request;
+	request.m_RequestType = static_cast<i8>(requestType);
 	request.m_RequestID = requestID;
 	m_Session->SendMessage(&request);
 }
diff --git a/source/network/NetFileTransfer.h b/source/network/NetFileTransfer.h
index f43e25b2a2..8689c4fa34 100644
--- a/source/network/NetFileTransfer.h
+++ b/source/network/NetFileTransfer.h
@@ -48,6 +48,12 @@ static const size_t MAX_FILE_TRANSFER_SIZE = 8*MiB;
 class CNetFileTransferer
 {
 public:
+	enum class RequestType
+	{
+		LOADGAME,
+		REJOIN
+	};
+
 	CNetFileTransferer(INetSession* session)
 		: m_Session(session), m_NextRequestID(1), m_LastProgressReportTime(0)
 	{
@@ -64,7 +70,7 @@ public:
 	/**
 	 * Registers a file-receiving task.
 	 */
-	void StartTask(std::function<void(std::string)> task);
+	void StartTask(RequestType requestType, std::function<void(std::string)> task);
 
 	/**
 	 * Registers data to be sent in response to a request.
diff --git a/source/network/NetMessages.h b/source/network/NetMessages.h
index f2259d0a7e..c6bdcb4f9d 100644
--- a/source/network/NetMessages.h
+++ b/source/network/NetMessages.h
@@ -155,6 +155,7 @@ START_NMT_CLASS_(PlayerAssignment, NMT_PLAYER_ASSIGNMENT)
 END_NMT_CLASS()
 
 START_NMT_CLASS_(FileTransferRequest, NMT_FILE_TRANSFER_REQUEST)
+	NMT_FIELD_INT(m_RequestType, i8, 1)
 	NMT_FIELD_INT(m_RequestID, u32, 4)
 END_NMT_CLASS()
 
diff --git a/source/network/NetServer.cpp b/source/network/NetServer.cpp
index 7f22be1a1b..9ad3a98e6e 100644
--- a/source/network/NetServer.cpp
+++ b/source/network/NetServer.cpp
@@ -623,6 +623,8 @@ void CNetServerWorker::HandleMessageReceive(const CNetMessage* message, CNetServ
 	if (message->GetType() == NMT_FILE_TRANSFER_REQUEST)
 	{
 		CFileTransferRequestMessage* reqMessage = (CFileTransferRequestMessage*)message;
+		ENSURE(static_cast<CNetFileTransferer::RequestType>(reqMessage->m_RequestType) ==
+			CNetFileTransferer::RequestType::REJOIN);
 
 		// Rejoining client got our JoinSyncStart after we received the state from
 		// another client, and has now requested that we forward it to them
@@ -1122,7 +1124,8 @@ bool CNetServerWorker::OnAuthenticate(CNetServerSession* session, CFsmEvent* eve
 	// copy from.
 	CNetServerSession* sourceSession = server.m_Sessions.at(0);
 
-	sourceSession->GetFileTransferer().StartTask([&server, newHostID](std::string buffer)
+	sourceSession->GetFileTransferer().StartTask(CNetFileTransferer::RequestType::REJOIN,
+		[&server, newHostID](std::string buffer)
 		{
 			// We've received the game state from an existing player - now we need to send it onwards
 			// to the newly rejoining player.
diff --git a/source/network/tests/test_FileTransfer.h b/source/network/tests/test_FileTransfer.h
index acef4e15fb..e3579152c0 100644
--- a/source/network/tests/test_FileTransfer.h
+++ b/source/network/tests/test_FileTransfer.h
@@ -89,7 +89,8 @@ public:
 
 		bool complete{false};
 
-		client.transferer.StartTask([&complete](std::string buffer)
+		client.transferer.StartTask(CNetFileTransferer::RequestType::LOADGAME,
+			[&complete](std::string buffer)
 			{
 				// This callback is executed exactly once.
 				const bool previousComplete{std::exchange(complete, true)};
@@ -121,4 +122,17 @@ public:
 		server.transferer.HandleMessageReceive(client.queues.acknowledgements.at(0));
 		CheckSizes(server.queues, 0, 1, 1, 0);
 	}
+
+	void test_RequestType()
+	{
+		for (const auto& requestType : {CNetFileTransferer::RequestType::LOADGAME,
+			CNetFileTransferer::RequestType::REJOIN})
+		{
+			Participant client;
+
+			client.transferer.StartTask(requestType, [](auto&&){});
+			TS_ASSERT_EQUALS(static_cast<CNetFileTransferer::RequestType>(
+				client.queues.requests.at(0).m_RequestType), requestType);
+		}
+	}
 };