diff --git a/OngekiFumenEditor/Modules/FumenVisualEditor/Graphics/Drawing/TargetImpl/VisibleLineVerticesQuery.cs b/OngekiFumenEditor/Modules/FumenVisualEditor/Graphics/Drawing/TargetImpl/VisibleLineVerticesQuery.cs
index 47250c2d..4a59ddf4 100644
--- a/OngekiFumenEditor/Modules/FumenVisualEditor/Graphics/Drawing/TargetImpl/VisibleLineVerticesQuery.cs
+++ b/OngekiFumenEditor/Modules/FumenVisualEditor/Graphics/Drawing/TargetImpl/VisibleLineVerticesQuery.cs
@@ -82,7 +82,8 @@ void CheckIfSoflanChanged2(double totalTGrid, bool isVailed)
                     if (diff < 0)
                     {
                         var xGrid = start.CalulateXGrid(checkTGrid);
-                        PostPoint(checkTGrid, xGrid, isVailed);
+                        if (xGrid is not null)
+                            PostPoint(checkTGrid, xGrid, isVailed);
                     }
 
                     affectedSoflanPoints.RemoveAt(affectedSoflanPoints.Count - 1);