diff --git a/DATabase/MergeDiff.cs b/DATabase/MergeDiff.cs
index 1b935bc1..4c17f7ed 100644
--- a/DATabase/MergeDiff.cs
+++ b/DATabase/MergeDiff.cs
@@ -115,6 +115,7 @@ namespace SabreTools
 			DatData userData = new DatData
 			{
 				Roms = new Dictionary<string, List<RomData>>(),
+				MergeRoms = _dedup,
 			};
 			foreach (string input in _inputs)
 			{