Index: src/Common/NetTopologySuite/Algorithm/CentroidPoint.cs
===================================================================
diff -u -r8f6ae890fed8e8eae3a32f9c0498a10f82e0ddf9 -r5fc71a385897af92ccb092f2f969b5709afab85a
--- src/Common/NetTopologySuite/Algorithm/CentroidPoint.cs	(.../CentroidPoint.cs)	(revision 8f6ae890fed8e8eae3a32f9c0498a10f82e0ddf9)
+++ src/Common/NetTopologySuite/Algorithm/CentroidPoint.cs	(.../CentroidPoint.cs)	(revision 5fc71a385897af92ccb092f2f969b5709afab85a)
@@ -11,28 +11,46 @@
     public class CentroidPoint
     {
         private int ptCount = 0;
-        private ICoordinate centSum = new Coordinate();
+        private readonly ICoordinate centSum = new Coordinate();
 
         /// <summary>
         /// 
         /// </summary>
-        public CentroidPoint() { }
+        public CentroidPoint() {}
 
+        /// <summary>
+        /// 
+        /// </summary>
+        public ICoordinate Centroid
+        {
+            get
+            {
+                ICoordinate cent = new Coordinate();
+                cent.X = centSum.X/ptCount;
+                cent.Y = centSum.Y/ptCount;
+                return cent;
+            }
+        }
+
         /// <summary> 
         /// Adds the point(s) defined by a Geometry to the centroid total.
         /// If the point is not of dimension 0 it does not contribute to the centroid.
         /// </summary>
         /// <param name="geom">The point to add.</param>
         public void Add(IGeometry geom)
         {
-            if (geom is IPoint)             
+            if (geom is IPoint)
+            {
                 Add(geom.Coordinate);
+            }
 
-            else if(geom is IGeometryCollection) 
+            else if (geom is IGeometryCollection)
             {
                 IGeometryCollection gc = (IGeometryCollection) geom;
                 foreach (IGeometry geometry in gc.Geometries)
+                {
                     Add(geometry);
+                }
             }
         }
 
@@ -46,19 +64,5 @@
             centSum.X += pt.X;
             centSum.Y += pt.Y;
         }
-
-        /// <summary>
-        /// 
-        /// </summary>
-        public ICoordinate Centroid
-        {
-            get
-            {
-                ICoordinate cent = new Coordinate();
-                cent.X = centSum.X / ptCount;
-                cent.Y = centSum.Y / ptCount;
-                return cent;
-            }
-        }
-    }   
-}
+    }
+}
\ No newline at end of file