fix for: https://issues.apache.org/jira/browse/AMQNET-390
diff --git a/src/main/csharp/Util/PrimitiveMap.cs b/src/main/csharp/Util/PrimitiveMap.cs
index dda5871..e62cfa1 100644
--- a/src/main/csharp/Util/PrimitiveMap.cs
+++ b/src/main/csharp/Util/PrimitiveMap.cs
@@ -375,7 +375,7 @@
 				MarshalPrimitiveMap(map, new EndianBinaryWriter(memoryStream));
 			}
 
-			return memoryStream.GetBuffer();
+			return memoryStream.ToArray();
 		}
 
 		public static void MarshalPrimitiveMap(IDictionary map, Stream stream)