diff --git a/src/TSMapEditor/Mutations/Classes/HeightMutations/LowerCellsMutation.cs b/src/TSMapEditor/Mutations/Classes/HeightMutations/LowerCellsMutation.cs
index 3b0f4a99..2985b0ef 100644
--- a/src/TSMapEditor/Mutations/Classes/HeightMutations/LowerCellsMutation.cs
+++ b/src/TSMapEditor/Mutations/Classes/HeightMutations/LowerCellsMutation.cs
@@ -45,6 +45,10 @@ public override void Perform()
             else
             {
                 var targetTile = MutationTarget.Map.GetTile(targetCellCoords);
+
+                if (targetTile == null || targetTile.Level <= 0)
+                    return;
+
                 var tilesToProcess = Helpers.GetFillAreaTiles(targetTile, MutationTarget.Map, MutationTarget.TheaterGraphics);
 
                 // Process tiles
diff --git a/src/TSMapEditor/Mutations/Classes/HeightMutations/RaiseCellsMutation.cs b/src/TSMapEditor/Mutations/Classes/HeightMutations/RaiseCellsMutation.cs
index 6251103a..82253d4d 100644
--- a/src/TSMapEditor/Mutations/Classes/HeightMutations/RaiseCellsMutation.cs
+++ b/src/TSMapEditor/Mutations/Classes/HeightMutations/RaiseCellsMutation.cs
@@ -46,6 +46,10 @@ public override void Perform()
             else
             {
                 var targetTile = MutationTarget.Map.GetTile(targetCellCoords);
+
+                if (targetTile == null || targetTile.Level >= Constants.MaxMapHeightLevel)
+                    return;
+
                 var tilesToProcess = Helpers.GetFillAreaTiles(targetTile, MutationTarget.Map, MutationTarget.TheaterGraphics);
 
                 // Process tiles