anchor.diff:              | None -> raise systemValueTupleException
           if isStruct then
               match tys.Length with 
  -            | 1 -> deOption(stuple1).MakeGenericType(tys)
  -            | 2 -> deOption(stuple2).MakeGenericType(tys)
  -            | 3 -> deOption(stuple3).MakeGenericType(tys)
  -            | 4 -> deOption(stuple4).MakeGenericType(tys)
  -            | 5 -> deOption(stuple5).MakeGenericType(tys)
  -            | 6 -> deOption(stuple6).MakeGenericType(tys)
  -            | 7 -> deOption(stuple7).MakeGenericType(tys)
  +            | 1 -> deOption(stuple1.Value).MakeGenericType(tys)
  +            | 2 -> deOption(stuple2.Value).MakeGenericType(tys)
  +            | 3 -> deOption(stuple3.Value).MakeGenericType(tys)
  +            | 4 -> deOption(stuple4.Value).MakeGenericType(tys)
  +            | 5 -> deOption(stuple5.Value).MakeGenericType(tys)
  +            | 6 -> deOption(stuple6.Value).MakeGenericType(tys)
  +            | 7 -> deOption(stuple7.Value).MakeGenericType(tys)
               | n when n >= maxTuple -> 
                   let tysA = tys.[0..tupleEncField-1]
                   let tysB = tys.[maxTuple-1..]
                   let tyB = mkTupleType isStruct tysB
  -                deOption(stuple8).MakeGenericType(Array.append tysA [| tyB |])
  +                deOption(stuple8.Value).MakeGenericType(Array.append tysA [| tyB |])
               | _ -> invalidArg "tys" (SR.GetString(SR.invalidTupleTypes))
           else
               match tys.Length with 
  
positive.code: 
      let mutable systemValueTupleException = null
  
      let reflectedValueTuple n =
          try        
  #if FX_ASSEMBLYLOADBYSTRING
              let a = Assembly.Load("System.ValueTuple")
  #else
              let a = Assembly.Load(new AssemblyName("System.ValueTuple"))
  #endif
              match n with
              | 1 -> Some (a.GetType("System.ValueTuple`1"))
              | 2 -> Some (a.GetType("System.ValueTuple`2"))
  
negative.code:             || isTuple8Type typ
  
          let isStructTupleType =
                 isStructTuple1Type typ
              || isStructTuple2Type typ
              || isStructTuple3Type typ
              || isStructTuple4Type typ
              || isStructTuple5Type typ
              || isStructTuple6Type typ
              || isStructTuple7Type typ
              || isStructTuple8Type typ
  
          isRefTupleType || isStructTupleType
  
      let maxTuple = 8
  