diff --git a/ChangeLog b/ChangeLog
index 3b2c0dc0b..fd668f810 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2004-05-18  Mike Kestner  <mkestner@ximian.com>
+
+	* glib/MissingIntPtrCtorException.cs : new exception to throw if 
+	unable to access an IntPtr ctor on a GLib.Object subclass.  We need
+	an IntPtr ctor to be able to wrap arbitrary object handles.
+	* glib/Object.cs : have NativeType call LookupGType.
+	* glib/ObjectManager.cs : throw the new exception in a try/catch.
+
 2004-05-17  Mike Kestner  <mkestner@ximian.com>
 
 	* generator/ObjectGen.cs : Generate a .cctor that calls the assembly's
diff --git a/glib/Makefile.am b/glib/Makefile.am
index ebe969416..6d70fef7f 100644
--- a/glib/Makefile.am
+++ b/glib/Makefile.am
@@ -26,6 +26,7 @@ sources =		 			\
 	ManagedValue.cs				\
 	Markup.cs				\
 	Marshaller.cs				\
+	MissingIntPtrCtorException.cs		\
 	Object.cs				\
 	ObjectManager.cs			\
 	Opaque.cs				\
diff --git a/glib/MissingIntPtrCtorException.cs b/glib/MissingIntPtrCtorException.cs
new file mode 100644
index 000000000..1f6d15b10
--- /dev/null
+++ b/glib/MissingIntPtrCtorException.cs
@@ -0,0 +1,20 @@
+// MissingIntPtrCtorException.cs : Exception for missing IntPtr ctors
+//
+// Authors: Mike Kestner  <mkestner@ximian.com>
+//
+// Copyright (c) 2004 Novell, Inc.
+
+namespace GLib {
+
+	using System;
+	using System.Runtime.InteropServices;
+	
+	public class MissingIntPtrCtorException : Exception
+	{
+		public MissingIntPtrCtorException (string msg) : base (msg)
+		{
+		}
+
+	}
+}
+
diff --git a/glib/Object.cs b/glib/Object.cs
index ede5150bc..c2142cfbb 100644
--- a/glib/Object.cs
+++ b/glib/Object.cs
@@ -207,10 +207,7 @@ namespace GLib {
 
 		internal GLib.GType NativeType {
 			get {
-				if (_obj == IntPtr.Zero)
-					return GType.Invalid;
-
-				return new GLib.GType (gtksharp_get_type_id (_obj));
+				return LookupGType ();
 			}
 		}
 
diff --git a/glib/ObjectManager.cs b/glib/ObjectManager.cs
index 22f8ac05c..76dd09d73 100644
--- a/glib/ObjectManager.cs
+++ b/glib/ObjectManager.cs
@@ -40,7 +40,13 @@ namespace GtkSharp {
 				return null;
 			}
 
-			return (GLib.Object) Activator.CreateInstance (t, new object[] {raw});
+			GLib.Object obj;
+			try {
+				obj = (GLib.Object) Activator.CreateInstance (t, new object[] {raw});
+			} catch (MissingMethodException) {
+				throw new GLib.MissingIntPtrCtorException ("All GLib.Object subclasses must provide a protected or public IntPtr ctor to support wrapping of native object handles.");
+			}
+			return obj;
 		}
 
 		public static void RegisterType (string native_name, string managed_name, string assembly)