1 files changed, 1 insertions, 1 deletions
diff --git a/src/mscorlib/shared/System/Runtime/InteropServices/ExternalException.cs b/src/mscorlib/shared/System/Runtime/InteropServices/ExternalException.cs
index d7bde79c43..81b9a46928 100644
--- a/src/mscorlib/shared/System/Runtime/InteropServices/ExternalException.cs
+++ b/src/mscorlib/shared/System/Runtime/InteropServices/ExternalException.cs
@@ -21,7 +21,6 @@ namespace System.Runtime.InteropServices
     // Base exception for COM Interop errors &; Structured Exception Handler
     // exceptions.
     // 
-    [Serializable]
     public class ExternalException : SystemException
     {
         public ExternalException()
@@ -51,6 +50,7 @@ namespace System.Runtime.InteropServices
         protected ExternalException(SerializationInfo info, StreamingContext context)
             : base(info, context)
         {
+            throw new PlatformNotSupportedException();
         }
 
         public virtual int ErrorCode