diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7d408a8d1..380c6f6d3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,6 +28,7 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
 -   Fixed conversion of 'float' and 'double' values (#486)
 -   Fixed 'clrmethod' for python 2 (#492)
 -   Fixed double calling of constructor when deriving from .NET class (#495)
+-   Fixed `clr.GetClrType` when iterating over `System` members (#607) 
 
 
 ## [2.3.0][] - 2017-03-11
diff --git a/src/runtime/managedtype.cs b/src/runtime/managedtype.cs
index 562b2e5f8..3191da949 100644
--- a/src/runtime/managedtype.cs
+++ b/src/runtime/managedtype.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Runtime.InteropServices;
 
 namespace Python.Runtime
@@ -34,6 +34,10 @@ internal static ManagedType GetManagedObject(IntPtr ob)
                     IntPtr op = tp == ob
                         ? Marshal.ReadIntPtr(tp, TypeOffset.magic())
                         : Marshal.ReadIntPtr(ob, ObjectOffset.magic(ob));
+                    if (op == IntPtr.Zero)
+                    {
+                        return null;
+                    }
                     var gc = (GCHandle)op;
                     return (ManagedType)gc.Target;
                 }