diff --git a/include/boost/fiber/algorithm.hpp b/include/boost/fiber/algorithm.hpp
index 3aa56001..29aacf10 100644
--- a/include/boost/fiber/algorithm.hpp
+++ b/include/boost/fiber/algorithm.hpp
@@ -8,6 +8,7 @@
 
 #include <boost/assert.hpp>
 #include <boost/config.hpp>
+#include <boost/move/move.hpp>
 #include <boost/thread/locks.hpp>
 #include <boost/utility.hpp>
 
@@ -29,11 +30,9 @@ namespace fibers {
 
 struct BOOST_FIBERS_DECL algorithm : private noncopyable
 {
-    virtual void add( detail::fiber_base::ptr_t const&) = 0;
+    virtual void priority( BOOST_RV_REF( fiber), int) = 0;
 
-    virtual void priority( detail::fiber_base::ptr_t const&, int) = 0;
-
-    virtual void join( detail::fiber_base::ptr_t const&) = 0;
+    virtual void join( BOOST_RV_REF( fiber) ) = 0;
 
     virtual detail::fiber_base::ptr_t active() = 0;
 
@@ -43,6 +42,10 @@ struct BOOST_FIBERS_DECL algorithm : private noncopyable
 
     virtual void yield() = 0;
 
+    virtual void migrate_to( fiber const&) = 0;
+
+    virtual fiber steel_from() = 0;
+
     virtual ~algorithm() {}
 };
 
diff --git a/include/boost/fiber/detail/fiber_base.hpp b/include/boost/fiber/detail/fiber_base.hpp
index ee5debed..97fa4cd4 100644
--- a/include/boost/fiber/detail/fiber_base.hpp
+++ b/include/boost/fiber/detail/fiber_base.hpp
@@ -26,7 +26,7 @@
 #include <boost/fiber/detail/spinlock.hpp>
 #include <boost/fiber/detail/states.hpp>
 
-#include <boost/thread.hpp>
+#include <boost/shared_ptr.hpp>
 
 #ifdef BOOST_HAS_ABI_HEADERS
 #  include BOOST_ABI_PREFIX
@@ -39,7 +39,13 @@ namespace detail {
 class BOOST_FIBERS_DECL fiber_base : private noncopyable
 {
 public:
-    typedef intrusive_ptr< fiber_base >           ptr_t;
+    struct deleter
+    {
+        void operator()( fiber_base * f)
+        { f->deallocate_object(); }
+    };
+    typedef shared_ptr< fiber_base >           ptr_t;
+    //typedef intrusive_ptr< fiber_base >           ptr_t;
 
 private:
     template< typename X, typename Y, typename Z >
@@ -69,7 +75,7 @@ public:
         friend class fiber_base;
 
         fiber_base::ptr_t   impl_;
-
+    public:
         explicit id( fiber_base::ptr_t const& impl) BOOST_NOEXCEPT :
             impl_( impl)
         {}
diff --git a/include/boost/fiber/fiber.hpp b/include/boost/fiber/fiber.hpp
index 5a85d93f..e259ff21 100644
--- a/include/boost/fiber/fiber.hpp
+++ b/include/boost/fiber/fiber.hpp
@@ -53,7 +53,7 @@ private:
     typedef base_t::ptr_t         ptr_t;
     typedef void ( dummy::*safe_bool)();
 
-    static void spawn_( detail::fiber_base::ptr_t const&);
+    static void spawn_( fiber &);
 
     ptr_t       impl_;
 
@@ -66,7 +66,7 @@ public:
         impl_()
     {}
 
-    explicit fiber( ptr_t const& impl) BOOST_NOEXCEPT :
+    fiber( ptr_t const& impl) BOOST_NOEXCEPT :
         impl_( impl)
     {}
 
@@ -85,8 +85,8 @@ public:
         object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( forward< fiber_fn >( fn), attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( forward< fiber_fn >( fn), attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 
     template< typename StackAllocator >
@@ -101,8 +101,8 @@ public:
         object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( forward< fiber_fn >( fn), attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( forward< fiber_fn >( fn), attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 
     template< typename StackAllocator, typename Allocator >
@@ -117,8 +117,8 @@ public:
         object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( forward< fiber_fn >( fn), attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( forward< fiber_fn >( fn), attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 #endif
     template< typename Fn >
@@ -137,8 +137,8 @@ public:
         typename object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( forward< Fn >( fn), attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( forward< Fn >( fn), attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 
     template< typename Fn, typename StackAllocator >
@@ -157,8 +157,8 @@ public:
         typename object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( forward< Fn >( fn), attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( forward< Fn >( fn), attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
     template< typename Fn, typename StackAllocator, typename Allocator >
     explicit fiber( BOOST_RV_REF( Fn) fn, attributes const& attr,
@@ -176,8 +176,8 @@ public:
         typename object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( forward< Fn >( fn), attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( forward< Fn >( fn), attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 #else
     template< typename Fn >
@@ -196,8 +196,8 @@ public:
         typename object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 
     template< typename Fn, typename StackAllocator >
@@ -216,8 +216,8 @@ public:
         typename object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 
     template< typename Fn, typename StackAllocator, typename Allocator >
@@ -236,8 +236,8 @@ public:
         typename object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 
     template< typename Fn >
@@ -256,8 +256,8 @@ public:
         typename object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 
     template< typename Fn, typename StackAllocator >
@@ -276,8 +276,8 @@ public:
         typename object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 
     template< typename Fn, typename StackAllocator, typename Allocator >
@@ -296,8 +296,8 @@ public:
         typename object_t::allocator_t a( alloc);
         impl_ = ptr_t(
             // placement new
-            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a) );
-        spawn_( impl_);
+            ::new( a.allocate( 1) ) object_t( fn, attr, stack_alloc, a), detail::fiber_base::deleter() );
+        spawn_( * this);
     }
 #endif
 
@@ -317,16 +317,23 @@ public:
     }
 
     operator safe_bool() const BOOST_NOEXCEPT
-    { return joinable() ? & dummy::nonnull : 0; }
+    { return ( ! empty() && ! impl_->is_terminated() ) ? & dummy::nonnull : 0; }
 
     bool operator!() const BOOST_NOEXCEPT
-    { return ! joinable(); }
+    { return empty() || impl_->is_terminated(); }
+
+    void swap( fiber & other) BOOST_NOEXCEPT
+    { impl_.swap( other.impl_); }
+
+    bool empty() const BOOST_NOEXCEPT
+    { return 0 == impl_.get(); }
 
     bool joinable() const BOOST_NOEXCEPT
-    { return impl_ && ! impl_->is_terminated(); }
+    { return ! empty(); }
 
     id get_id() const BOOST_NOEXCEPT
-    { return impl_ ? impl_->get_id() : id(); }
+    { return impl_ ? id( impl_) : id(); }
+    //{ return impl_ ? impl_->get_id() : id(); }
 
     int priority() const BOOST_NOEXCEPT;
 
@@ -338,9 +345,6 @@ public:
     void join();
 
     void interrupt() BOOST_NOEXCEPT;
-
-    void swap( fiber & other) BOOST_NOEXCEPT
-    { impl_.swap( other.impl_); }
 };
 
 inline
diff --git a/include/boost/fiber/round_robin.hpp b/include/boost/fiber/round_robin.hpp
index 2718cec6..f1588146 100644
--- a/include/boost/fiber/round_robin.hpp
+++ b/include/boost/fiber/round_robin.hpp
@@ -12,7 +12,6 @@
 
 #include <boost/assert.hpp>
 #include <boost/config.hpp>
-#include <boost/move/move.hpp>
 #include <boost/thread/locks.hpp>
 
 #include <boost/fiber/detail/config.hpp>
@@ -50,8 +49,6 @@ public:
 
     ~round_robin() BOOST_NOEXCEPT;
 
-    void add( detail::fiber_base::ptr_t const&);
-
     void priority( detail::fiber_base::ptr_t const&, int);
 
     void join( detail::fiber_base::ptr_t const&);
@@ -65,7 +62,7 @@ public:
 
     void yield();
 
-    void migrate_to( BOOST_RV_REF( fiber) f);
+    void migrate_to( fiber const&);
 
     fiber steel_from();
 };
diff --git a/src/detail/fiber_base.cpp b/src/detail/fiber_base.cpp
index a9f4e98f..8b7f0de5 100644
--- a/src/detail/fiber_base.cpp
+++ b/src/detail/fiber_base.cpp
@@ -71,7 +71,7 @@ fiber_base::release()
     // so they can be resumed
     // protect against concurrent access to joining_
     unique_lock< spinlock > lk( joining_mtx_);
-    BOOST_FOREACH( fiber_base::ptr_t & p, joining_)
+    BOOST_FOREACH( fiber_base::ptr_t p, joining_)
     {
         std::stringstream ss;
         ss << p->get_id();
diff --git a/src/fiber.cpp b/src/fiber.cpp
index 9fe0a09a..59a0cf48 100644
--- a/src/fiber.cpp
+++ b/src/fiber.cpp
@@ -25,8 +25,8 @@ namespace boost {
 namespace fibers {
 
 void
-fiber::spawn_( detail::fiber_base::ptr_t const& f)
-{ detail::scheduler::instance().add( f); }
+fiber::spawn_( fiber & f)
+{ detail::scheduler::instance().migrate_to( f); }
 
 int
 fiber::priority() const
diff --git a/src/mutex.cpp b/src/mutex.cpp
index 0c3a770b..98cdbb9f 100644
--- a/src/mutex.cpp
+++ b/src/mutex.cpp
@@ -34,7 +34,7 @@ mutex::lock()
 {
     while ( LOCKED == state_.exchange( LOCKED, memory_order_seq_cst) )
     {
-        if ( ! this_fiber::is_fiberized() ) ::abort();
+        BOOST_ASSERT( this_fiber::is_fiberized() );
 
         unique_lock< detail::spinlock > lk( waiting_mtx_);
         waiting_.push_back(
diff --git a/src/round_robin.cpp b/src/round_robin.cpp
index a2fdbbbc..7a36f417 100644
--- a/src/round_robin.cpp
+++ b/src/round_robin.cpp
@@ -54,16 +54,6 @@ round_robin::~round_robin()
 #endif
 }
 
-void
-round_robin::add( detail::fiber_base::ptr_t const& f)
-{
-    BOOST_ASSERT( f);
-    BOOST_ASSERT( ! f->is_running() );
-    BOOST_ASSERT( ! f->is_terminated() );
-
-    wqueue_.push_back( f);
-}
-
 bool
 round_robin::run()
 {
@@ -228,9 +218,14 @@ round_robin::priority( detail::fiber_base::ptr_t const& f, int prio)
 }
 
 void
-round_robin::migrate_to( BOOST_RV_REF( fiber) f)
+round_robin::migrate_to( fiber const& f_)
 {
-    add( detail::scheduler::extract( f) );
+    detail::fiber_base::ptr_t f = detail::scheduler::extract( f_);
+    BOOST_ASSERT( f);
+    BOOST_ASSERT( ! f->is_running() );
+    BOOST_ASSERT( ! f->is_terminated() );
+
+    wqueue_.push_back( f);
 }
 
 fiber
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index cffe5208..07a3a44f 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -24,7 +24,7 @@ rule fiber-test ( source )
 }
 
 test-suite fibers :
-#  [ fiber-test test_fiber ]
+  [ fiber-test test_fiber ]
 #  [ fiber-test test_mutex ]
 #  [ fiber-test test_condition ]
 #  [ fiber-test test_generic_locks ]
@@ -34,5 +34,5 @@ test-suite fibers :
 #  [ fiber-test test_futures ]
 #  [ fiber-test test_then ]
 #  [ fiber-test test_round_robin ]
-  [ fiber-test test_fiber_steeling ]
+#  [ fiber-test test_fiber_steeling ]
 ;
diff --git a/test/test_fiber_steeling.cpp b/test/test_fiber_steeling.cpp
index af9e055c..a07d2d40 100644
--- a/test/test_fiber_steeling.cpp
+++ b/test/test_fiber_steeling.cpp
@@ -89,10 +89,10 @@ void fn_steel_fibers( boost::fibers::round_robin * other_ds, boost::barrier * b,
         if ( f)
         {
             ++( * count);
-            ds.migrate_to( boost::move( f) );
+            ds.migrate_to( f);
             while ( boost::fibers::run() );
         }
-        BOOST_ASSERT( ! f);
+        f.detach();
     }
 }