diff --git a/Packages/nadena.dev.modular-avatar/Editor/ClonedMenuMappings.cs b/Packages/nadena.dev.modular-avatar/Editor/ClonedMenuMappings.cs
index 85e54c46..9f245929 100644
--- a/Packages/nadena.dev.modular-avatar/Editor/ClonedMenuMappings.cs
+++ b/Packages/nadena.dev.modular-avatar/Editor/ClonedMenuMappings.cs
@@ -7,8 +7,8 @@ namespace nadena.dev.modular_avatar.core.editor
 {
 	public static class ClonedMenuMappings 
 	{
-		private static readonly Dictionary<VRCExpressionsMenu, ImmutableArray<VRCExpressionsMenu>> ClonedMappings =
-			new Dictionary<VRCExpressionsMenu, ImmutableArray<VRCExpressionsMenu>>();
+		private static readonly Dictionary<VRCExpressionsMenu, ImmutableList<VRCExpressionsMenu>> ClonedMappings =
+			new Dictionary<VRCExpressionsMenu, ImmutableList<VRCExpressionsMenu>>();
 
 		private static readonly Dictionary<VRCExpressionsMenu, VRCExpressionsMenu> OriginalMapping =
 			new Dictionary<VRCExpressionsMenu, VRCExpressionsMenu>();
@@ -21,16 +21,15 @@ namespace nadena.dev.modular_avatar.core.editor
 
 		public static void Add(VRCExpressionsMenu original, VRCExpressionsMenu clonedMenu) 
 		{
-			if (!ClonedMappings.TryGetValue(original, out ImmutableArray<VRCExpressionsMenu> clonedMenus)) 
+			if (!ClonedMappings.TryGetValue(original, out ImmutableList<VRCExpressionsMenu> clonedMenus)) 
 			{
-				clonedMenus = ImmutableArray<VRCExpressionsMenu>.Empty;
+				clonedMenus = ImmutableList<VRCExpressionsMenu>.Empty;
 			}
-			// Usually, one menu is rarely duplicated in multiple menus, so don't bother using a Builder
 			ClonedMappings[original] = clonedMenus.Add(clonedMenu);
 			OriginalMapping[clonedMenu] = original;
 		}
 
-		public static bool TryGetClonedMenus(VRCExpressionsMenu original, out ImmutableArray<VRCExpressionsMenu> clonedMenus) 
+		public static bool TryGetClonedMenus(VRCExpressionsMenu original, out ImmutableList<VRCExpressionsMenu> clonedMenus) 
 		{
 			return ClonedMappings.TryGetValue(original, out clonedMenus);
 		}
diff --git a/Packages/nadena.dev.modular-avatar/Editor/MenuTree.cs b/Packages/nadena.dev.modular-avatar/Editor/MenuTree.cs
index 1f56c10e..9a5be2fd 100644
--- a/Packages/nadena.dev.modular-avatar/Editor/MenuTree.cs
+++ b/Packages/nadena.dev.modular-avatar/Editor/MenuTree.cs
@@ -125,7 +125,7 @@ namespace nadena.dev.modular_avatar.core.editor
 			IEnumerable<KeyValuePair<string, VRCExpressionsMenu>> childMenus = GetChildMenus(installer.menuToAppend);
 			IEnumerable<VRCExpressionsMenu> parents = Enumerable.Empty<VRCExpressionsMenu>();
 			if (installer.installTargetMenu != null &&
-			    ClonedMenuMappings.TryGetClonedMenus(installer.installTargetMenu, out ImmutableArray<VRCExpressionsMenu> parentMenus)) 
+			    ClonedMenuMappings.TryGetClonedMenus(installer.installTargetMenu, out ImmutableList<VRCExpressionsMenu> parentMenus)) 
 			{
 				parents = parentMenus;
 			}