diff --git a/ChangeLog b/ChangeLog
index bf7c380f7..a03fb99b1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2008-10-12  Andrés G. Aragoneses  <aaragoneses@novell.com>
+
+	Fixes BNC#426876.
+	* generator/InterfaceGen.cs: throw ArgumentNullException in
+	the Adapter's constructor that receives an implementor.
+
 2008-10-09  Mike Kestner  <mkestner@novell.com>
 
 	* cairo/*.cs: flatten source hierarchy to simplify win32 build.
diff --git a/generator/InterfaceGen.cs b/generator/InterfaceGen.cs
index 1b20cb3b9..2319c9839 100644
--- a/generator/InterfaceGen.cs
+++ b/generator/InterfaceGen.cs
@@ -170,6 +170,8 @@ namespace GtkSharp.Generation {
 			sw.WriteLine ();
 			sw.WriteLine ("\t\tpublic {0}Adapter ({0}Implementor implementor)", Name);
 			sw.WriteLine ("\t\t{");
+			sw.WriteLine ("\t\t\tif (implementor == null)");
+			sw.WriteLine ("\t\t\t\tthrow new ArgumentNullException (\"implementor\");");
 			sw.WriteLine ("\t\t\tthis.implementor = implementor;");
 			sw.WriteLine ("\t\t}");
 			sw.WriteLine ();