diff --git a/MindBox.Lib/FlatShape.cs b/MindBox.Lib/FlatShape.cs
index aa43312..d168ddd 100644
--- a/MindBox.Lib/FlatShape.cs
+++ b/MindBox.Lib/FlatShape.cs
@@ -3,8 +3,5 @@ namespace MindBox.Lib;
 public abstract class FlatShape : ITwoDimensional
 {
 	protected double? _area;
-	public virtual double GetArea()
-	{
-		throw new NotImplementedException();
-	}
+	public abstract double GetArea();
 }