diff --git a/MatterControlLib/PartPreviewWindow/View3D/Actions/SheetEditor.cs b/MatterControlLib/PartPreviewWindow/View3D/Actions/SheetEditor.cs
index ce1dd1a46..a952da42b 100644
--- a/MatterControlLib/PartPreviewWindow/View3D/Actions/SheetEditor.cs
+++ b/MatterControlLib/PartPreviewWindow/View3D/Actions/SheetEditor.cs
@@ -181,7 +181,10 @@ namespace MatterHackers.MatterControl.DesignTools
             // first replace spaces with '_'
             var name = editSelectedName.Text.Replace(' ', '_');
 			// next make sure we don't have the exact name already
-			name = agg_basics.GetNonCollidingName(name, existingNames, false);
+			name = agg_basics.GetNonCollidingName(name, (name) =>
+			{
+				return !existingNames.Contains(name.ToLower());
+			}, false);
 			editSelectedName.Text = name;
 			SheetData[selectedCell.x, selectedCell.y].Name = name;
 			SheetData.Recalculate();