diff --git a/include/boost/fiber/condition.hpp b/include/boost/fiber/condition.hpp
index 0b0f319c..99460d27 100644
--- a/include/boost/fiber/condition.hpp
+++ b/include/boost/fiber/condition.hpp
@@ -16,7 +16,6 @@
 #include <boost/config.hpp>
 #include <boost/detail/scoped_enum_emulation.hpp>
 #include <boost/thread/locks.hpp>
-#include <boost/thread/thread.hpp>
 #include <boost/utility.hpp>
 
 #include <boost/fiber/detail/config.hpp>
@@ -104,8 +103,7 @@ public:
                 lt.unlock();
                 while ( ! n->is_ready() )
                     // run scheduler
-                    if ( ! detail::scheduler::instance()->run() )
-                        this_thread::yield();
+                    detail::scheduler::instance()->run();
             }
         }
         catch (...)
@@ -178,8 +176,7 @@ public:
                         break;
                     }
                     // run scheduler
-                    if ( ! detail::scheduler::instance()->run() )
-                        this_thread::yield();
+                    detail::scheduler::instance()->run();
                 }
             }
         }
diff --git a/include/boost/fiber/operations.hpp b/include/boost/fiber/operations.hpp
index 031e50e6..2379f72c 100644
--- a/include/boost/fiber/operations.hpp
+++ b/include/boost/fiber/operations.hpp
@@ -7,7 +7,6 @@
 #define BOOST_THIS_FIBER_OPERATIONS_H
 
 #include <boost/thread/lock_types.hpp> 
-#include <boost/thread/thread.hpp> 
 
 #include <boost/fiber/algorithm.hpp>
 #include <boost/fiber/detail/config.hpp>
@@ -35,12 +34,9 @@ inline
 void yield()
 {
     if ( fibers::detail::scheduler::instance()->active() )
-    { fibers::detail::scheduler::instance()->yield(); }
+        fibers::detail::scheduler::instance()->yield();
     else
-    {
-        if ( ! fibers::detail::scheduler::instance()->run() )
-            this_thread::yield();
-    }
+        fibers::detail::scheduler::instance()->run();
 }
 
 inline
@@ -58,8 +54,7 @@ void sleep_until( fibers::clock_type::time_point const& sleep_time)
     else
     {
         while ( fibers::clock_type::now() <= sleep_time)
-            if ( ! fibers::detail::scheduler::instance()->run() )
-                this_thread::yield();
+            fibers::detail::scheduler::instance()->run();
     }
 }
 
diff --git a/src/mutex.cpp b/src/mutex.cpp
index b5d70d63..8d3a4801 100644
--- a/src/mutex.cpp
+++ b/src/mutex.cpp
@@ -9,7 +9,6 @@
 #include <algorithm>
 
 #include <boost/assert.hpp>
-#include <boost/thread/thread.hpp>
 
 #include "boost/fiber/detail/scheduler.hpp"
 #include "boost/fiber/interruption.hpp"
@@ -85,8 +84,7 @@ mutex::lock()
             // wait until main-fiber gets notified
             while ( ! n->is_ready() )
                 // run scheduler
-                if ( ! detail::scheduler::instance()->run() )
-                    this_thread::yield();
+                detail::scheduler::instance()->run();
         }
     }
 }
diff --git a/src/recursive_mutex.cpp b/src/recursive_mutex.cpp
index 6c032d18..eab8dbdd 100644
--- a/src/recursive_mutex.cpp
+++ b/src/recursive_mutex.cpp
@@ -9,7 +9,6 @@
 #include <algorithm>
 
 #include <boost/assert.hpp>
-#include <boost/thread/thread.hpp>
 
 #include "boost/fiber/detail/scheduler.hpp"
 #include "boost/fiber/interruption.hpp"
@@ -99,8 +98,7 @@ recursive_mutex::lock()
             // wait until main-fiber gets notified
             while ( ! n->is_ready() )
                 // run scheduler
-                if ( ! detail::scheduler::instance()->run() )
-                    this_thread::yield();
+                detail::scheduler::instance()->run();
         }
     }
 }
diff --git a/src/recursive_timed_mutex.cpp b/src/recursive_timed_mutex.cpp
index 0b107883..00d17dc5 100644
--- a/src/recursive_timed_mutex.cpp
+++ b/src/recursive_timed_mutex.cpp
@@ -9,7 +9,6 @@
 #include <algorithm>
 
 #include <boost/assert.hpp>
-#include <boost/thread/thread.hpp>
 
 #include "boost/fiber/detail/scheduler.hpp"
 #include "boost/fiber/interruption.hpp"
@@ -99,8 +98,7 @@ recursive_timed_mutex::lock()
             // wait until main-fiber gets notified
             while ( ! n->is_ready() )
                 // run scheduler
-                if ( ! detail::scheduler::instance()->run() )
-                    this_thread::yield();
+                detail::scheduler::instance()->run();
         }
     }
 }
@@ -218,8 +216,7 @@ recursive_timed_mutex::try_lock_until( clock_type::time_point const& timeout_tim
                     return false;
                 }
                 // run scheduler
-                if ( ! detail::scheduler::instance()->run() )
-                    this_thread::yield();
+                detail::scheduler::instance()->run();
             }
         }
     }
diff --git a/src/round_robin.cpp b/src/round_robin.cpp
index d958443b..bf546d97 100644
--- a/src/round_robin.cpp
+++ b/src/round_robin.cpp
@@ -96,7 +96,11 @@ round_robin::run()
     detail::fiber_base::ptr_t f;
     do
     {
-        if ( rqueue_.empty() ) return false;
+        if ( rqueue_.empty() )
+        {
+            this_thread::yield();
+            return false;
+        }
         f.swap( rqueue_.front() );
         rqueue_.pop_front();
         if ( f->is_ready() ) break;
diff --git a/src/round_robin_ws.cpp b/src/round_robin_ws.cpp
index 0ec48315..0a13133c 100644
--- a/src/round_robin_ws.cpp
+++ b/src/round_robin_ws.cpp
@@ -96,7 +96,11 @@ round_robin_ws::run()
     detail::fiber_base::ptr_t f;
     do
     {
-        if ( ! rqueue_.try_pop( f) ) return false;
+        if ( ! rqueue_.try_pop( f) )
+        {
+            this_thread::yield();
+            return false;
+        }
         if ( f->is_ready() ) break;
         else BOOST_ASSERT_MSG( false, "fiber with invalid state in ready-queue");
     }
diff --git a/src/timed_mutex.cpp b/src/timed_mutex.cpp
index 57b9e556..a5ae9567 100644
--- a/src/timed_mutex.cpp
+++ b/src/timed_mutex.cpp
@@ -9,7 +9,6 @@
 #include <algorithm>
 
 #include <boost/assert.hpp>
-#include <boost/thread/thread.hpp>
 
 #include "boost/fiber/detail/scheduler.hpp"
 #include "boost/fiber/interruption.hpp"
@@ -85,8 +84,7 @@ timed_mutex::lock()
             // wait until main-fiber gets notified
             while ( ! n->is_ready() )
                 // run scheduler
-                if ( ! detail::scheduler::instance()->run() )
-                    this_thread::yield();
+                detail::scheduler::instance()->run();
         }
     }
 }
@@ -186,8 +184,7 @@ timed_mutex::try_lock_until( clock_type::time_point const& timeout_time)
                     return false;
                 }
                 // run scheduler
-                if ( ! detail::scheduler::instance()->run() )
-                    this_thread::yield();
+                detail::scheduler::instance()->run();
             }
         }
     }