Index: src/Common/NetTopologySuite/Algorithm/SimplePointInRing.cs
===================================================================
diff -u -r8f6ae890fed8e8eae3a32f9c0498a10f82e0ddf9 -r5fc71a385897af92ccb092f2f969b5709afab85a
--- src/Common/NetTopologySuite/Algorithm/SimplePointInRing.cs	(.../SimplePointInRing.cs)	(revision 8f6ae890fed8e8eae3a32f9c0498a10f82e0ddf9)
+++ src/Common/NetTopologySuite/Algorithm/SimplePointInRing.cs	(.../SimplePointInRing.cs)	(revision 5fc71a385897af92ccb092f2f969b5709afab85a)
@@ -11,7 +11,7 @@
         /// <summary>
         /// 
         /// </summary>
-        private ICoordinate[] pts;
+        private readonly ICoordinate[] pts;
 
         /// <summary>
         /// 
@@ -32,4 +32,4 @@
             return CGAlgorithms.IsPointInRing(pt, pts);
         }
     }
-}
+}
\ No newline at end of file