diff -Naur a/boost/multi_index_container.hpp b/boost/multi_index_container.hpp
--- a/boost/multi_index_container.hpp	2011-11-27 19:22:14.000000000 +0530
+++ b/boost/multi_index_container.hpp	2012-11-27 16:02:34.000000000 +0530
@@ -270,7 +270,7 @@
   }
 
   multi_index_container<Value,IndexSpecifierList,Allocator>& operator=(
-    multi_index_container<Value,IndexSpecifierList,Allocator> x)
+    multi_index_container<Value,IndexSpecifierList,Allocator>& x)
   {
     BOOST_MULTI_INDEX_CHECK_INVARIANT;
     this->swap(x);