1 files changed, 2 insertions, 2 deletions
diff --git a/csharp/src/ProtocolBuffers/GeneratedMessage.cs b/csharp/src/ProtocolBuffers/GeneratedMessage.cs
index 6f4b6657..c17c15cf 100644
--- a/csharp/src/ProtocolBuffers/GeneratedMessage.cs
+++ b/csharp/src/ProtocolBuffers/GeneratedMessage.cs
@@ -75,8 +75,8 @@ namespace Google.ProtocolBuffers
 
         internal IDictionary<FieldDescriptor, Object> GetMutableFieldMap()
         {
-            // Use a SortedList so we'll end up serializing fields in order
-            var ret = new SortedList<FieldDescriptor, object>();
+            // Use a SortedDictionary so we'll end up serializing fields in order
+            var ret = new SortedDictionary<FieldDescriptor, object>();
             MessageDescriptor descriptor = DescriptorForType;
             foreach (FieldDescriptor field in descriptor.Fields)
             {