@@ -12,6 +12,10 @@
     <None Include="fixtures/**/*.py" CopyToOutputDirectory="PreserveNewest" />
   </ItemGroup>
 
+  <PropertyGroup>
+    <DefineConstants>$(DefineConstants);$(ConfiguredConstants)</DefineConstants>
+  </PropertyGroup>
+
   <ItemGroup>
     <PackageReference Include="NUnit" Version="3.*" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.*">
 
@@ -0,0 +1,45 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+
+using NUnit.Framework;
+
+using Python.Runtime;
+
+namespace Python.EmbeddingPythonTest
+{
+    public class TestNativeTypeOffset
+    {
+        private Py.GILState _gs;
+
+        [SetUp]
+        public void SetUp()
+        {
+            _gs = Py.GIL();
+        }
+
+        [TearDown]
+        public void Dispose()
+        {
+            _gs.Dispose();
+        }
+
+        /// <summary>
+        /// Tests that installation has generated code for NativeTypeOffset and that it can be loaded.
+        /// </summary>        
+        [Test]
+        public void LoadNativeTypeOffsetClass()
+        {
+            PyObject sys = Py.Import("sys");
+            string attributeName = "abiflags";
+            if (sys.HasAttr(attributeName) && !string.IsNullOrEmpty(sys.GetAttr(attributeName).ToString()))
+            {
+                string typeName = "Python.Runtime.NativeTypeOffset, Python.Runtime";
+                Assert.NotNull(Type.GetType(typeName), $"{typeName} does not exist and sys.{attributeName} is not empty");
+            }
+        }
+    }
+}
@@ -19,12 +19,6 @@
     <DefineConstants>$(DefineConstants);$(ConfiguredConstants)</DefineConstants>
   </PropertyGroup>
 
-  <ItemGroup Condition=" '$(PythonInteropFile)' != '' ">
-    <Compile Remove="interop*.cs" />
-    <Compile Include="interop.cs" />
-    <Compile Include="$(PythonInteropFile)" />
-  </ItemGroup>
-
   <ItemGroup>
     <None Remove="resources\clr.py" />
     <EmbeddedResource Include="resources\clr.py">
 
@@ -22,7 +22,12 @@ internal static void Initialize(Version version, BorrowedReference pyType)
                 thisAssembly.GetType(nativeTypeOffsetClassName, throwOnError: false)
                 ?? thisAssembly.GetType(className, throwOnError: false);
             if (typeOffsetsClass is null)
-                throw new NotSupportedException($"Python ABI v{version} is not supported");
+            {
+                var types = thisAssembly.GetTypes().Select(type => type.Name).Where(name => name.StartsWith("TypeOffset"));
+                string message = $"Searching for {className}, found {string.Join(",", types)}. " +
+                    "If you are building Python.NET from source, make sure you have run 'python setup.py configure' to fill in configured.props";
+                throw new NotSupportedException($"Python ABI v{version} is not supported: {message}");
+            }
             var typeOffsets = (ITypeOffsets)Activator.CreateInstance(typeOffsetsClass);
             TypeOffset.Use(typeOffsets);