diff --git a/src/AST/Class.cs b/src/AST/Class.cs
index aa756db2..cce81845 100644
--- a/src/AST/Class.cs
+++ b/src/AST/Class.cs
@@ -145,7 +145,7 @@ namespace CppSharp.AST
 
         public bool IsRefType
         {
-            get { return Type == ClassType.RefType; }
+            get { return Type == ClassType.RefType && !IsUnion; }
         }
 
         public IEnumerable<Method> Constructors
diff --git a/src/Generator/Generators/CLI/CLIMarshal.cs b/src/Generator/Generators/CLI/CLIMarshal.cs
index 6e1e6d90..e9634456 100644
--- a/src/Generator/Generators/CLI/CLIMarshal.cs
+++ b/src/Generator/Generators/CLI/CLIMarshal.cs
@@ -180,7 +180,7 @@ namespace CppSharp.Generators.CLI
 
             if (@class.IsRefType)
             {
-                var name = Helpers.GeneratedIdentifier(Context.ReturnVarName);
+                var name = Generator.GeneratedIdentifier(Context.ReturnVarName);
                 Context.SupportBefore.WriteLine("auto {0} = new ::{1}({2});", name,
                     @class.QualifiedOriginalName, Context.ReturnVarName);
                 instance = name;
diff --git a/src/Generator/Generators/CLI/CLISourcesTemplate.cs b/src/Generator/Generators/CLI/CLISourcesTemplate.cs
index 1a13b35e..8f87ae90 100644
--- a/src/Generator/Generators/CLI/CLISourcesTemplate.cs
+++ b/src/Generator/Generators/CLI/CLISourcesTemplate.cs
@@ -740,7 +740,8 @@ namespace CppSharp.Generators.CLI
             var @params = GenerateFunctionParamsMarshal(function.Parameters, function);
 
             if (needsReturn)
-                Write("auto {0}ret = ",(function.ReturnType.Type.IsReference())? "&": string.Empty);
+                Write("auto {0}{1} = ",(function.ReturnType.Type.IsReference())? "&": string.Empty,
+                    Generator.GeneratedIdentifier("ret"));
 
             if (!IsNativeFunctionOrStaticMethod(function))
             {
@@ -799,8 +800,8 @@ namespace CppSharp.Generators.CLI
             {
                 var ctx = new MarshalContext(Driver)
                     {
-                        ArgName = "ret",
-                        ReturnVarName = "ret",
+                        ArgName = Generator.GeneratedIdentifier("ret"),
+                        ReturnVarName = Generator.GeneratedIdentifier("ret"),
                         ReturnType = retType
                     };
 
diff --git a/src/Generator/Generators/CSharp/CSharpMarshal.cs b/src/Generator/Generators/CSharp/CSharpMarshal.cs
index 545cd683..08de1719 100644
--- a/src/Generator/Generators/CSharp/CSharpMarshal.cs
+++ b/src/Generator/Generators/CSharp/CSharpMarshal.cs
@@ -185,7 +185,7 @@ namespace CppSharp.Generators.CSharp
             FunctionType function;
             if (decl.Type.IsPointerTo(out function))
             {
-                var ptrName = Helpers.GeneratedIdentifier("ptr") +
+                var ptrName = Generator.GeneratedIdentifier("ptr") +
                     Context.ParameterIndex;
 
                 Context.SupportBefore.WriteLine("var {0} = {1};", ptrName,
@@ -206,12 +206,15 @@ namespace CppSharp.Generators.CSharp
             string instance = Context.ReturnVarName;
             if (ctx.Kind == CSharpMarshalKind.NativeField)
             {
-                instance = string.Format("new global::System.IntPtr(&{0})", instance);
+                string copy = Generator.GeneratedIdentifier("copy");
+                Context.SupportBefore.WriteLine(
+                    "var {0} = new global::System.IntPtr(&{1});", copy, instance);
+                instance = copy;
             }
 
             if (@class.IsRefType)
             {
-                var instanceName = Helpers.GeneratedIdentifier("instance");
+                var instanceName = Generator.GeneratedIdentifier("instance");
 
                 // Allocate memory for a new native object and call the ctor.
                 Context.SupportBefore.WriteLine("var {0} = Marshal.AllocHGlobal({1});",
@@ -363,17 +366,17 @@ namespace CppSharp.Generators.CSharp
                 if (Context.Parameter.Usage == ParameterUsage.Out)
                 {
                     Context.SupportBefore.WriteLine("var {0} = new {1}.Internal();",
-                        Helpers.GeneratedIdentifier(Context.ArgName), @class.Name);
+                        Generator.GeneratedIdentifier(Context.ArgName), @class.Name);
                 }
                 else
                 {
                     Context.SupportBefore.WriteLine("var {0} = {1}.ToInternal();",
-                            Helpers.GeneratedIdentifier(Context.ArgName),
+                            Generator.GeneratedIdentifier(Context.ArgName),
                             Helpers.SafeIdentifier(Context.Parameter.Name));
                 }
 
                 Context.Return.Write("new global::System.IntPtr(&{0})",
-                    Helpers.GeneratedIdentifier(Context.ArgName));
+                    Generator.GeneratedIdentifier(Context.ArgName));
                 return true;
             }
 
diff --git a/src/Generator/Generators/CSharp/CSharpTextTemplate.cs b/src/Generator/Generators/CSharp/CSharpTextTemplate.cs
index 97a758ea..2e40d40b 100644
--- a/src/Generator/Generators/CSharp/CSharpTextTemplate.cs
+++ b/src/Generator/Generators/CSharp/CSharpTextTemplate.cs
@@ -26,11 +26,6 @@ namespace CppSharp.Generators.CSharp
                 "void", "partial", "yield", "where"
             };
 
-        public static string GeneratedIdentifier(string id)
-        {
-            return "_" + id;
-        }
-
         public static string SafeIdentifier(string id)
         {
             id = new string(((IEnumerable<char>)id)
@@ -59,7 +54,7 @@ namespace CppSharp.Generators.CSharp
 
         public static string InstanceIdentifier
         {
-            get { return GeneratedIdentifier("Instance"); }
+            get { return Generator.GeneratedIdentifier("Instance"); }
         }
     }
 
@@ -124,7 +119,7 @@ namespace CppSharp.Generators.CSharp
 
         public static string GeneratedIdentifier(string id)
         {
-            return Helpers.GeneratedIdentifier(id);
+            return Generator.GeneratedIdentifier(id);
         }
 
         public static string SafeIdentifier(string id)
@@ -216,7 +211,7 @@ namespace CppSharp.Generators.CSharp
             if (context.HasFunctions)
             {
                 PushBlock(CSharpBlockKind.Functions);
-                WriteLine("public partial class {0}{1}", SafeIdentifier(Options.OutputNamespace),
+                WriteLine("public unsafe partial class {0}{1}", SafeIdentifier(Options.OutputNamespace),
                     TranslationUnit.FileNameWithoutExtension);
                 WriteStartBraceIndent();
 
@@ -324,8 +319,8 @@ namespace CppSharp.Generators.CSharp
                 if (ShouldGenerateClassNativeField(@class))
                 {
                     PushBlock(CSharpBlockKind.Field);
-                    WriteLine("public global::System.IntPtr {0} {{ get; protected set; }}",
-                        Helpers.InstanceIdentifier);
+                    WriteLine("public global::System.IntPtr {0} {{ get; {1} set; }}",
+                        Helpers.InstanceIdentifier, @class.IsValueType ? "private" : "protected");
                     PopBlock(NewLineKind.BeforeNextBlock);
                 }
 
@@ -513,7 +508,7 @@ namespace CppSharp.Generators.CSharp
                 if (ASTUtils.CheckIgnoreField(field)) continue;
 
                 var nativeField = string.Format("{0}->{1}",
-                    Helpers.GeneratedIdentifier("ptr"), field.OriginalName);
+                    Generator.GeneratedIdentifier("ptr"), field.OriginalName);
 
                 var ctx = new CSharpMarshalContext(Driver)
                 {
@@ -535,9 +530,9 @@ namespace CppSharp.Generators.CSharp
 
         private void GenerateStructInternalMarshaling(Class @class)
         {
-            var marshalVar = Helpers.GeneratedIdentifier("native");
+            var marshalVar = Generator.GeneratedIdentifier("native");
 
-            WriteLine("var {0} = new {1}.Internal();", marshalVar, @class.Name);
+            WriteLine("var {0} = new {1}.Internal();", marshalVar, QualifiedIdentifier(@class));
             GenerateStructInternalMarshalingFields(@class, marshalVar);
 
             WriteLine("return {0};", marshalVar);
@@ -746,7 +741,7 @@ namespace CppSharp.Generators.CSharp
                 var field = decl as Field;
 
                 WriteLine("var {0} = (Internal*){1}.ToPointer();",
-                    Helpers.GeneratedIdentifier("ptr"), Helpers.InstanceIdentifier);
+                    Generator.GeneratedIdentifier("ptr"), Helpers.InstanceIdentifier);
 
                 var marshal = new CSharpMarshalManagedToNativePrinter(ctx);
                 param.Visit(marshal);
@@ -754,7 +749,7 @@ namespace CppSharp.Generators.CSharp
                 if (!string.IsNullOrWhiteSpace(marshal.Context.SupportBefore))
                     Write(marshal.Context.SupportBefore);
 
-                Write("{0}->{1} = {2}", Helpers.GeneratedIdentifier("ptr"),
+                Write("{0}->{1} = {2}", Generator.GeneratedIdentifier("ptr"),
                     Helpers.SafeIdentifier(field.OriginalName), marshal.Context.Return);
 
                 WriteLine(";");
@@ -781,13 +776,13 @@ namespace CppSharp.Generators.CSharp
                 var field = decl as Field;
 
                 WriteLine("var {0} = (Internal*){1}.ToPointer();",
-                    Helpers.GeneratedIdentifier("ptr"), Helpers.InstanceIdentifier);
+                    Generator.GeneratedIdentifier("ptr"), Helpers.InstanceIdentifier);
 
                 var ctx = new CSharpMarshalContext(Driver)
                 {
                     Kind = CSharpMarshalKind.NativeField,
                     ArgName = decl.Name,
-                    ReturnVarName = string.Format("{0}->{1}", Helpers.GeneratedIdentifier("ptr"),
+                    ReturnVarName = string.Format("{0}->{1}", Generator.GeneratedIdentifier("ptr"),
                         Helpers.SafeIdentifier(field.OriginalName)),
                     ReturnType = decl.QualifiedType
                 };
@@ -810,7 +805,7 @@ namespace CppSharp.Generators.CSharp
                 var location = string.Format("CppSharp.SymbolResolver.ResolveSymbol(\"{0}\", \"{1}\")",
                     libSymbol.Item1, libSymbol.Item2);
 
-                WriteLine("var {0} = ({1}*){2};", Helpers.GeneratedIdentifier("ptr"),
+                WriteLine("var {0} = ({1}*){2};", Generator.GeneratedIdentifier("ptr"),
                     @var.Type, location);
 
                 TypePrinter.PopContext();
@@ -818,7 +813,7 @@ namespace CppSharp.Generators.CSharp
                 var ctx = new CSharpMarshalContext(Driver)
                 {
                     ArgName = decl.Name,
-                    ReturnVarName = "*" + Helpers.GeneratedIdentifier("ptr"),
+                    ReturnVarName = "*" + Generator.GeneratedIdentifier("ptr"),
                     ReturnType = new QualifiedType(var.Type)
                 };
 
@@ -1185,7 +1180,7 @@ namespace CppSharp.Generators.CSharp
             var args = TypePrinter.VisitParameters(@event.Parameters, hasNames: true);
             TypePrinter.PopContext();
 
-            delegateInstance = Helpers.GeneratedIdentifier(@event.OriginalName);
+            delegateInstance = Generator.GeneratedIdentifier(@event.OriginalName);
             delegateName = delegateInstance + "Delegate";
             delegateRaise = delegateInstance + "RaiseInstance";
 
@@ -1221,7 +1216,7 @@ namespace CppSharp.Generators.CSharp
             WriteLine("{0} = new {1}(_{2}Raise);", delegateRaise, delegateName, @event.Name);
 
             WriteLine("var {0} = Marshal.GetFunctionPointerForDelegate({1}).ToPointer();",
-                Helpers.GeneratedIdentifier("ptr"), delegateInstance);
+                Generator.GeneratedIdentifier("ptr"), delegateInstance);
 
             // Call type map here.
 
@@ -1362,7 +1357,8 @@ namespace CppSharp.Generators.CSharp
             PopBlock(NewLineKind.BeforeNextBlock);
 
             PushBlock(CSharpBlockKind.Method);
-            WriteLine("internal {0}(global::System.IntPtr native)", SafeIdentifier(@class.Name));
+            WriteLine("internal {0}(global::System.IntPtr native){1}", SafeIdentifier(@class.Name),
+                @class.IsValueType ? " : this()" : string.Empty);
 
             var hasBaseClass = @class.HasBaseClass && @class.BaseClass.IsRefType;
             if (hasBaseClass)
@@ -1376,13 +1372,13 @@ namespace CppSharp.Generators.CSharp
                 {
                     WriteLine("{0} = native;", Helpers.InstanceIdentifier);
                     if (Options.GenerateVirtualTables && @class.IsDynamic)
-                        WriteLine("SetupVTables(_Instance);");
+                        WriteLine("SetupVTables({0});", Generator.GeneratedIdentifier("Instance"));
                 }
             }
             else
             {
                 WriteLine("var {0} = (Internal*){1}.ToPointer();",
-                    Helpers.GeneratedIdentifier("ptr"), "native");
+                    Generator.GeneratedIdentifier("ptr"), "native");
                 GenerateStructMarshalingFields(@class);
             }
 
@@ -1401,7 +1397,7 @@ namespace CppSharp.Generators.CSharp
                 PushBlock(CSharpBlockKind.Method);
                 WriteLine("internal void FromInternal(Internal* native)");
                 WriteStartBraceIndent();
-                WriteLine("var {0} = {1};", Helpers.GeneratedIdentifier("ptr"), "native");
+                WriteLine("var {0} = {1};", Generator.GeneratedIdentifier("ptr"), "native");
                 GenerateStructMarshalingFields(@class);
                 WriteCloseBraceIndent();
                 PopBlock(NewLineKind.BeforeNextBlock);
@@ -1580,7 +1576,7 @@ namespace CppSharp.Generators.CSharp
             GenerateFunctionParams(@params);
             WriteLine(");");
             if (Options.GenerateVirtualTables && @class.IsDynamic)
-                WriteLine("SetupVTables(_Instance);");
+                WriteLine("SetupVTables({0});", Generator.GeneratedIdentifier("Instance"));
         }
 
         public void GenerateInternalFunctionCall(Function function,
@@ -1636,7 +1632,7 @@ namespace CppSharp.Generators.CSharp
 
                 Class retClass = null;
                 hiddenParam.Type.Desugar().IsTagDecl(out retClass);
-                WriteLine("var ret = new {0}.Internal();", retClass.OriginalName);
+                WriteLine("var {0} = new {1}.Internal();", GeneratedIdentifier("ret"), QualifiedIdentifier(retClass));
             }
 
             var names = new List<string>();
@@ -1653,7 +1649,7 @@ namespace CppSharp.Generators.CSharp
 
             if (function.HasHiddenStructParameter)
             {
-                var name = string.Format("new IntPtr(&ret)");
+                var name = string.Format("new IntPtr(&{0})", GeneratedIdentifier("ret"));
                 names.Insert(0, name);
             }
 
@@ -1668,11 +1664,11 @@ namespace CppSharp.Generators.CSharp
                 //WriteLine("fixed({0}* {1} = &this)", @class.QualifiedName,
                 //    GeneratedIdentifier("instance"));
                 //WriteStartBraceIndent();
-                WriteLine("var {0} = ToInternal();", Helpers.GeneratedIdentifier("instance"));
+                WriteLine("var {0} = ToInternal();", Generator.GeneratedIdentifier("instance"));
             }
 
             if (needsReturn && !function.HasHiddenStructParameter)
-                Write("var ret = ");
+                Write("var {0} = ", GeneratedIdentifier("ret"));
 
             WriteLine("{0}({1});", functionName, string.Join(", ", names));
 
@@ -1696,15 +1692,15 @@ namespace CppSharp.Generators.CSharp
             if (needsFixedThis)
             {
                 //    WriteCloseBraceIndent();
-                WriteLine("FromInternal(&{0});", Helpers.GeneratedIdentifier("instance"));
+                WriteLine("FromInternal(&{0});", Generator.GeneratedIdentifier("instance"));
             }
 
             if (needsReturn)
             {
                 var ctx = new CSharpMarshalContext(Driver)
                 {
-                    ArgName = "ret",
-                    ReturnVarName = "ret",
+                    ArgName = GeneratedIdentifier("ret"),
+                    ReturnVarName = GeneratedIdentifier("ret"),
                     ReturnType = retType
                 };
 
diff --git a/src/Generator/Generators/Generator.cs b/src/Generator/Generators/Generator.cs
index 87a05003..9f078639 100644
--- a/src/Generator/Generators/Generator.cs
+++ b/src/Generator/Generators/Generator.cs
@@ -98,5 +98,10 @@ namespace CppSharp.Generators
         /// Generates the outputs for a given translation unit.
         /// </summary>
         public abstract List<Template> Generate(TranslationUnit unit);
+
+        public static string GeneratedIdentifier(string id)
+        {
+            return "__" + id;
+        }
     }
 }
\ No newline at end of file
diff --git a/src/Generator/Passes/CheckOperatorsOverloads.cs b/src/Generator/Passes/CheckOperatorsOverloads.cs
index bb35ad02..c6f6a79b 100644
--- a/src/Generator/Passes/CheckOperatorsOverloads.cs
+++ b/src/Generator/Passes/CheckOperatorsOverloads.cs
@@ -1,5 +1,6 @@
 using System.Linq;
 using CppSharp.AST;
+using CppSharp.Generators;
 using CppSharp.Generators.CSharp;
 
 namespace CppSharp.Passes
@@ -64,7 +65,7 @@ namespace CppSharp.Passes
 
                 @operator.Parameters.Insert(0, new Parameter
                 {
-                    Name = Helpers.GeneratedIdentifier("op"),
+                    Name = Generator.GeneratedIdentifier("op"),
                     QualifiedType = new QualifiedType(type),
                     Kind = ParameterKind.OperatorParameter
                 });
diff --git a/tests/Basic/Basic.cpp b/tests/Basic/Basic.cpp
index 99ea4654..4b01f651 100644
--- a/tests/Basic/Basic.cpp
+++ b/tests/Basic/Basic.cpp
@@ -69,4 +69,9 @@ Foo Hello::RetFoo(int a, float b)
 int Hello::RetEnum(Enum e)
 {
     return (int)e;
-}
\ No newline at end of file
+}
+
+int unsafeFunction(const Bar& ret)
+{
+    return ret.A;
+}
diff --git a/tests/Basic/Basic.h b/tests/Basic/Basic.h
index 4a464848..079be9bd 100644
--- a/tests/Basic/Basic.h
+++ b/tests/Basic/Basic.h
@@ -15,6 +15,10 @@ public:
 
 class DLL_API Foo2 : public Foo
 {
+    struct Copy {
+        Foo A;
+    }* copy;
+
 public:
 
     int C;
@@ -42,6 +46,11 @@ enum Enum
 
 class DLL_API Hello
 {
+    union {
+        int i;
+        float b;
+    };
+
 public:
     Hello ();
 
@@ -60,4 +69,6 @@ public:
     int AddBar2(Bar2);
 
     int RetEnum(Enum);
-};
\ No newline at end of file
+};
+
+int DLL_API unsafeFunction(const Bar& ret);