diff --git a/include/boost/fiber/operations.hpp b/include/boost/fiber/operations.hpp
index 20aaa699..bd69968c 100644
--- a/include/boost/fiber/operations.hpp
+++ b/include/boost/fiber/operations.hpp
@@ -39,9 +39,7 @@ void yield() {
 
 template< typename Clock, typename Duration >
 void sleep_until( std::chrono::time_point< Clock, Duration > const& sleep_time) {
-    fibers::detail::spinlock splk;
-    std::unique_lock< fibers::detail::spinlock > lk( splk);
-    fibers::context::active()->do_wait_until( sleep_time, lk);
+    fibers::context::active()->do_wait_until( sleep_time);
 
     // check if fiber was interrupted
     interruption_point();
diff --git a/src/context.cpp b/src/context.cpp
index 1e56b908..fb41cefa 100644
--- a/src/context.cpp
+++ b/src/context.cpp
@@ -57,7 +57,7 @@ context::release() {
     splk_.unlock();
 
     // notify all waiting fibers
-    for ( context * f : wait_queue_) {
+    for ( context * f : tmp) {
         do_signal( f);
     }