diff --git a/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Editing/Flatten.cs b/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Editing/Flatten.cs
index df34eeb8b2..0946c6ac5d 100644
--- a/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Editing/Flatten.cs
+++ b/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Editing/Flatten.cs
@@ -109,10 +109,8 @@ namespace libTerrain
                     z *= z;
                     z -= ((x - rx)*(x - rx)) + ((y - ry)*(y - ry));
 
-                    if (z < 0)
-                        z = 0;
-
-                    Set(x, y, Tools.LinearInterpolate(map[x, y], height, z));
+                    if (z > 0.0)
+                        Set(x, y, Tools.LinearInterpolate(map[x, y], height, z));
                 }
             }
         }
diff --git a/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Editing/Raise.cs b/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Editing/Raise.cs
index 9a8b8f5694..0173400c9b 100644
--- a/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Editing/Raise.cs
+++ b/OpenSim/Region/Terrain.BasicTerrain/libTerrainBSD/Channel/Editing/Raise.cs
@@ -63,10 +63,8 @@ namespace libTerrain
                     z *= z;
                     z -= ((x - rx)*(x - rx)) + ((y - ry)*(y - ry));
 
-                    if (z < 0)
-                        z = 0;
-
-                    Set(x, y, map[x, y] + (z*amount));
+                    if (z > 0.0)
+                        Set(x, y, map[x, y] + (z * amount));
                 }
             }
         }
@@ -88,10 +86,8 @@ namespace libTerrain
                     double z = size;
                     z -= Math.Sqrt(((x - rx)*(x - rx)) + ((y - ry)*(y - ry)));
 
-                    if (z < 0)
-                        z = 0;
-
-                    Set(x, y, map[x, y] + (z*amount));
+                    if (z > 0.0)
+                        Set(x, y, map[x, y] + (z * amount));
                 }
             }
         }
@@ -126,10 +122,8 @@ namespace libTerrain
                     z *= z;
                     z -= ((x - rx)*(x - rx)) + ((y - ry)*(y - ry));
 
-                    if (z < 0)
-                        z = 0;
-
-                    Set(x, y, map[x, y] - (z*amount));
+                    if (z > 0.0)
+                        Set(x, y, map[x, y] + (z * amount));
                 }
             }
         }