diff --git a/src/Generator/Types/Std/Stdlib.cs b/src/Generator/Types/Std/Stdlib.cs
index 515b2f03..6eb17bb7 100644
--- a/src/Generator/Types/Std/Stdlib.cs
+++ b/src/Generator/Types/Std/Stdlib.cs
@@ -315,8 +315,9 @@ namespace CppSharp.Types.Std
 
         public override void CLIMarshalToNative(MarshalContext ctx)
         {
-            var marshal = ctx.MarshalToNative as CLIMarshalManagedToNativePrinter;
-            marshal.ArgumentPrefix.Write("*");
+            var marshal = (CLIMarshalManagedToNativePrinter) ctx.MarshalToNative;
+            if (!ctx.Parameter.Type.Desugar().IsPointer())
+                marshal.ArgumentPrefix.Write("*");
             var marshalCtxName = string.Format("ctx_{0}", ctx.Parameter.Name);
             ctx.SupportBefore.WriteLine("msclr::interop::marshal_context {0};", marshalCtxName);
             ctx.Return.Write("{0}.marshal_as<std::ostream*>({1})",
diff --git a/tests/STL/STL.h b/tests/STL/STL.h
index e9c04dea..3220da3a 100644
--- a/tests/STL/STL.h
+++ b/tests/STL/STL.h
@@ -36,4 +36,9 @@ struct DLL_API OStreamTest
     {
         stream << s;
     };
-};
\ No newline at end of file
+
+    static void WriteToOStreamPtr(std::ostream* stream, const char* s)
+    {
+        *stream << s;
+    };
+};