diff --git a/src/Generator/Generators/CLI/CLISourcesTemplate.cs b/src/Generator/Generators/CLI/CLISourcesTemplate.cs
index b9568359..c3c9e76c 100644
--- a/src/Generator/Generators/CLI/CLISourcesTemplate.cs
+++ b/src/Generator/Generators/CLI/CLISourcesTemplate.cs
@@ -1101,7 +1101,12 @@ namespace CppSharp.Generators.CLI
                 var type = paramType.Visit(typePrinter);
 
                 if (param.IsInOut)
+                {
+                    if (!string.IsNullOrWhiteSpace(marshal.Context.SupportBefore))
+                        Write(marshal.Context.SupportBefore);
+
                     WriteLine("{0} {1} = {2};", type, argName, marshal.Context.Return);
+                }
                 else
                     WriteLine("{0} {1};", type, argName);
             }
diff --git a/src/Generator/Generators/CSharp/CSharpMarshal.cs b/src/Generator/Generators/CSharp/CSharpMarshal.cs
index 34198090..0366c35d 100644
--- a/src/Generator/Generators/CSharp/CSharpMarshal.cs
+++ b/src/Generator/Generators/CSharp/CSharpMarshal.cs
@@ -435,6 +435,11 @@ namespace CppSharp.Generators.CSharp
                     Context.Return.Write("IntPtr.Zero");
                     CSharpContext.ArgumentPrefix.Write("&");
                 }
+                else if (Context.Parameter.IsInOut)
+                {
+                    Context.Return.Write(MarshalStringToUnmanaged(Context.Parameter.Name));
+                    CSharpContext.ArgumentPrefix.Write("&");
+                }
                 else
                 {
                     Context.Return.Write(MarshalStringToUnmanaged(Context.Parameter.Name));
diff --git a/tests/Basic/Basic.Tests.cs b/tests/Basic/Basic.Tests.cs
index 7893748e..cb9eac03 100644
--- a/tests/Basic/Basic.Tests.cs
+++ b/tests/Basic/Basic.Tests.cs
@@ -67,6 +67,9 @@ public class BasicTests : GeneratorTestFixture
         Assert.That(str, Is.EqualTo("HelloStringOut"));
         hello.StringOutRef(out str);
         Assert.That(str, Is.EqualTo("HelloStringOutRef"));
+        str = "Hello";
+        hello.StringInOut(ref str);
+        Assert.That(str, Is.EqualTo("StringInOut"));
     }
     
     [Test]
diff --git a/tests/Basic/Basic.cpp b/tests/Basic/Basic.cpp
index c992e5ee..e405f60d 100644
--- a/tests/Basic/Basic.cpp
+++ b/tests/Basic/Basic.cpp
@@ -1,4 +1,5 @@
 #include "Basic.h"
+#include <string.h>
 
 Foo::Foo()
 {
@@ -213,6 +214,14 @@ void Hello::StringOutRef(CS_OUT const char*& str)
 	str = "HelloStringOutRef";
 }
 
+void Hello::StringInOut(CS_IN_OUT const char** str)
+{
+	if (strcmp(*str, "Hello") == 0)
+		*str = "StringInOut";
+	else
+		*str = "Failed";
+}
+
 int unsafeFunction(const Bar& ret, char* testForString, void (*foo)(int))
 {
     return ret.A;
diff --git a/tests/Basic/Basic.h b/tests/Basic/Basic.h
index 7dcd7d65..9f7318eb 100644
--- a/tests/Basic/Basic.h
+++ b/tests/Basic/Basic.h
@@ -135,6 +135,8 @@ public:
 
     void StringOut(CS_OUT const char** str);
     void StringOutRef(CS_OUT const char*& str);
+    void StringInOut(CS_IN_OUT const char** str);
+    //void StringInOutRef(CS_OUT const char*& str);
 };
 
 class DLL_API AbstractFoo