diff --git a/netfx_loader/ClrLoader.cs b/netfx_loader/ClrLoader.cs
index 2a065bb..472ff4a 100644
--- a/netfx_loader/ClrLoader.cs
+++ b/netfx_loader/ClrLoader.cs
@@ -3,6 +3,7 @@
 using System.IO;
 using System.Reflection;
 using System.Runtime.InteropServices;
+using System.Text;
 using NXPorts.Attributes;
 
 namespace ClrLoader
@@ -12,6 +13,21 @@ public static class ClrLoader
         static bool _initialized = false;
         static List<DomainData> _domains = new List<DomainData>();
 
+        private static string PtrToStringUtf8(IntPtr ptr)
+        {
+            if (ptr == IntPtr.Zero)
+                return null;
+
+            int len = 0;
+            while (Marshal.ReadByte(ptr, len) != 0)
+                len++;
+
+            byte[] bytes = new byte[len];
+            Marshal.Copy(ptr, bytes, 0, len);
+
+            return Encoding.UTF8.GetString(bytes);
+        }
+
         [DllExport("pyclr_initialize", CallingConvention.Cdecl)]
         public static void Initialize()
         {
@@ -36,11 +52,10 @@ private static string AssemblyDirectory
         }
 
         [DllExport("pyclr_create_appdomain", CallingConvention.Cdecl)]
-        public static IntPtr CreateAppDomain(
-            [MarshalAs(UnmanagedType.LPUTF8Str)] string name,
-            [MarshalAs(UnmanagedType.LPUTF8Str)] string configFile
-        )
+        public static IntPtr CreateAppDomain(IntPtr namePtr, IntPtr configFilePtr)
         {
+            string name = PtrToStringUtf8(namePtr);
+            string configFile = PtrToStringUtf8(configFilePtr);
             Print($"Creating AppDomain {name} with {configFile}");
 
             var clrLoaderDir = AssemblyDirectory;
@@ -68,13 +83,16 @@ public static IntPtr CreateAppDomain(
         [DllExport("pyclr_get_function", CallingConvention.Cdecl)]
         public static IntPtr GetFunction(
             IntPtr domain,
-            [MarshalAs(UnmanagedType.LPUTF8Str)] string assemblyPath,
-            [MarshalAs(UnmanagedType.LPUTF8Str)] string typeName,
-            [MarshalAs(UnmanagedType.LPUTF8Str)] string function
+            IntPtr assemblyPathPtr,
+            IntPtr typeNamePtr,
+            IntPtr functionPtr
         )
         {
             try
             {
+                string assemblyPath = PtrToStringUtf8(assemblyPathPtr);
+                string typeName = PtrToStringUtf8(typeNamePtr);
+                string function = PtrToStringUtf8(functionPtr);
                 var domainData = _domains[(int)domain];
                 Print($"Getting functor for function {function} of type {typeName} in assembly {assemblyPath}");
                 return domainData.GetFunctor(assemblyPath, typeName, function);
diff --git a/netfx_loader/ClrLoader.csproj b/netfx_loader/ClrLoader.csproj
index 42f5ef8..e1283f1 100644
--- a/netfx_loader/ClrLoader.csproj
+++ b/netfx_loader/ClrLoader.csproj
@@ -1,6 +1,6 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net472</TargetFrameworks>
+    <TargetFrameworks>net461</TargetFrameworks>
     <RuntimeIdentifiers>win-x86;win-x64</RuntimeIdentifiers>
   </PropertyGroup>
 
diff --git a/netfx_loader/DomainData.cs b/netfx_loader/DomainData.cs
index 35c3363..24adeb9 100644
--- a/netfx_loader/DomainData.cs
+++ b/netfx_loader/DomainData.cs
@@ -38,13 +38,13 @@ class DomainData : IDisposable
         bool _disposed = false;
 
         public AppDomain Domain { get; }
-        public Dictionary<(string, string, string), IntPtr> _functors;
+        public Dictionary<Tuple<string, string, string>, IntPtr> _functors;
         public HashSet<string> _resolvedAssemblies;
 
         public DomainData(AppDomain domain)
         {
             Domain = domain;
-            _functors = new Dictionary<(string, string, string), IntPtr>();
+            _functors = new Dictionary<Tuple<string, string, string>, IntPtr>();
             _resolvedAssemblies = new HashSet<string>();
         }
 
@@ -76,7 +76,7 @@ public IntPtr GetFunctor(string assemblyPath, string typeName, string function)
                 installResolver(assemblyPath);
                 var assemblyName = AssemblyName.GetAssemblyName(assemblyPath).Name;
 
-                var key = (assemblyName, typeName, function);
+                var key = Tuple.Create(assemblyName, typeName, function);
 
                 IntPtr result;
                 if (!_functors.TryGetValue(key, out result))