Index: Riskeer/Common/src/Riskeer.Common.Data/MechanismSurfaceLineBase.cs
===================================================================
diff -u -r0940a966479ed0c2225bd96fd27efae945f9e51e -rae086aefd228d3bc765e9d0b4b92dae66735704b
--- Riskeer/Common/src/Riskeer.Common.Data/MechanismSurfaceLineBase.cs	(.../MechanismSurfaceLineBase.cs)	(revision 0940a966479ed0c2225bd96fd27efae945f9e51e)
+++ Riskeer/Common/src/Riskeer.Common.Data/MechanismSurfaceLineBase.cs	(.../MechanismSurfaceLineBase.cs)	(revision ae086aefd228d3bc765e9d0b4b92dae66735704b)
@@ -190,7 +190,7 @@
             Point2D firstLocalPoint = LocalGeometry.First();
             Point2D lastLocalPoint = LocalGeometry.Last();
             var roundedLocalCoordinateL = new RoundedDouble(numberOfDecimalPlaces, localCoordinateL);
-            return !(firstLocalPoint.X > roundedLocalCoordinateL) && !(lastLocalPoint.X < roundedLocalCoordinateL);
+            return firstLocalPoint.X <= roundedLocalCoordinateL && lastLocalPoint.X >= roundedLocalCoordinateL;
         }
 
         public override string ToString()
Index: Riskeer/MacroStabilityInwards/src/Riskeer.MacroStabilityInwards.Forms/Factories/MacroStabilityInwardsChartDataPointsFactory.cs
===================================================================
diff -u -r86594ccd7329d320872573a1d066fe18959d3cea -rae086aefd228d3bc765e9d0b4b92dae66735704b
--- Riskeer/MacroStabilityInwards/src/Riskeer.MacroStabilityInwards.Forms/Factories/MacroStabilityInwardsChartDataPointsFactory.cs	(.../MacroStabilityInwardsChartDataPointsFactory.cs)	(revision 86594ccd7329d320872573a1d066fe18959d3cea)
+++ Riskeer/MacroStabilityInwards/src/Riskeer.MacroStabilityInwards.Forms/Factories/MacroStabilityInwardsChartDataPointsFactory.cs	(.../MacroStabilityInwardsChartDataPointsFactory.cs)	(revision ae086aefd228d3bc765e9d0b4b92dae66735704b)
@@ -668,8 +668,8 @@
         private static bool AreaIsNotFlatLine(IEnumerable<Point2D> topLine, IEnumerable<Point2D> bottomLine)
         {
             return topLine.Count() != bottomLine.Count()
-                   || topLine.Where((t, i) => !(Math.Abs(t.X - bottomLine.ElementAt(i).X) < tolerance)
-                                              || !(Math.Abs(t.Y - bottomLine.ElementAt(i).Y) < tolerance)).Any();
+                   || topLine.Where((t, i) => Math.Abs(t.X - bottomLine.ElementAt(i).X) >= tolerance
+                                              || Math.Abs(t.Y - bottomLine.ElementAt(i).Y) >= tolerance).Any();
         }
 
         private static bool IsSurfaceLineAboveWaternetZone(IEnumerable<Point2D> surfaceLineLocalGeometry,