diff --git a/src/saveload/engine_sl.cpp b/src/saveload/engine_sl.cpp
--- a/src/saveload/engine_sl.cpp
+++ b/src/saveload/engine_sl.cpp
@@ -196,7 +196,7 @@ static void Load_EIDS()
 static const ChunkHandler engine_chunk_handlers[] = {
 	{ 'EIDS', Save_EIDS, Load_EIDS, nullptr, nullptr, CH_ARRAY },
 	{ 'ENGN', Save_ENGN, Load_ENGN, nullptr, nullptr, CH_ARRAY },
-	{ 'ENGS', nullptr,   Load_ENGS, nullptr, nullptr, CH_RIFF  },
+	{ 'ENGS', nullptr,   Load_ENGS, nullptr, nullptr, CH_READONLY  },
 };
 
 extern const ChunkHandlerTable _engine_chunk_handlers(engine_chunk_handlers);