diff --git a/src/PathFinder.cs b/src/PathFinder.cs
index 6c0f54c..7fd59d8 100644
--- a/src/PathFinder.cs
+++ b/src/PathFinder.cs
@@ -40,7 +40,7 @@ namespace OpenSim.Modules.PathFinding
                 {
                     for (int Y = 0; Y < m_scene.RegionInfo.RegionSizeY; Y++)
                     {
-                        float baseheight = (float)m_scene.Heightmap[X, Y];
+                        float baseheight = (float)m_scene.Heightmap[(int)m_scene.RegionInfo.RegionSizeX - X, (int)m_scene.RegionInfo.RegionSizeY - Y];
 
                         //Block the position then water is on this place.
                         if (baseheight <= m_scene.RegionInfo.RegionSettings.WaterHeight)