diff --git a/include/boost/fusion/support/sequence_base.hpp b/include/boost/fusion/support/sequence_base.hpp
index ed1fffc7..9d5c558f 100644
--- a/include/boost/fusion/support/sequence_base.hpp
+++ b/include/boost/fusion/support/sequence_base.hpp
@@ -1,5 +1,6 @@
 /*=============================================================================
     Copyright (c) 2001-2006 Joel de Guzman
+    Copyright (c) 2007 Tobias Schwinger
 
     Use, modification and distribution is subject to the Boost Software
     License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@@ -9,6 +10,7 @@
 #define FUSION_SEQUENCE_BASE_04182005_0737
 
 #include <boost/fusion/support/detail/compiler_config.hpp>
+#include <boost/mpl/begin_end_fwd.hpp>
 
 namespace boost { namespace fusion
 {
@@ -29,6 +31,17 @@ namespace boost { namespace fusion
             return static_cast<Sequence&>(*this);
         }
     };
+
+    struct fusion_sequence_tag;
+}}
+
+namespace boost { namespace mpl
+{
+    // Deliberately break mpl::begin, so it doesn't lie that a Fusion sequence
+    // is not an MPL sequence by returning mpl::void_. 
+    // In other words: Fusion Sequences are always MPL Sequences, but they can
+    // be incompletely defined.
+    template<> struct begin_impl< boost::fusion::fusion_sequence_tag >;
 }}
 
 #endif