diff --git a/ArcFormats/PalmTree/ArcAR.cs b/ArcFormats/PalmTree/ArcAR.cs
index 386cb677..fea06c3a 100644
--- a/ArcFormats/PalmTree/ArcAR.cs
+++ b/ArcFormats/PalmTree/ArcAR.cs
@@ -47,6 +47,7 @@ namespace GameRes.Formats.PalmTree
         public ArcOpener ()
         {
             Settings = null;
+            Extensions = new string[] { "arc" };
         }
 
         public override ArcFile TryOpen (ArcView file)