diff --git a/src/scheduler.h b/src/scheduler.h
index 2029637848..376472f555 100644
--- a/src/scheduler.h
+++ b/src/scheduler.h
@@ -1,121 +1,122 @@
 // Copyright (c) 2015 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_SCHEDULER_H
 #define BITCOIN_SCHEDULER_H
 
 #include <sync.h>
 
 //
 // NOTE:
 // boost::thread / boost::chrono should be ported to
 // std::thread / std::chrono when we support C++11.
 //
 #include <boost/chrono/chrono.hpp>
 #include <boost/thread.hpp>
 
 #include <map>
 
 //
 // Simple class for background tasks that should be run periodically or once
 // "after a while"
 //
 // Usage:
 //
 // CScheduler* s = new CScheduler();
 // s->scheduleFromNow(doSomething, 11); // Assuming a: void doSomething() { }
 // s->scheduleFromNow(std::bind(Class::func, this, argument), 3);
 // boost::thread* t = new boost::thread(boost::bind(CScheduler::serviceQueue,
 // s));
 //
 // ... then at program shutdown, clean up the thread running serviceQueue:
 // t->interrupt();
 // t->join();
 // delete t;
 // delete s; // Must be done after thread is interrupted/joined.
 //
 
 class CScheduler {
 public:
     CScheduler();
     ~CScheduler();
 
     typedef std::function<void(void)> Function;
     typedef std::function<bool(void)> Predicate;
 
     // Call func at/after time t
     void schedule(Function f, boost::chrono::system_clock::time_point t =
                                   boost::chrono::system_clock::now());
 
     // Convenience method: call f once deltaMilliSeconds from now
     void scheduleFromNow(Function f, int64_t deltaMilliSeconds);
 
     // Another convenience method: call f approximately every deltaMilliSeconds
     // forever, starting deltaMilliSeconds from now. To be more precise: every
     // time f is finished, it is rescheduled to run deltaMilliSeconds later. If
     // you need more accurate scheduling, don't use this method.
     void scheduleEvery(Predicate p, int64_t deltaMilliSeconds);
 
     // To keep things as simple as possible, there is no unschedule.
 
     // Services the queue 'forever'. Should be run in a thread, and interrupted
     // using boost::interrupt_thread
     void serviceQueue();
 
     // Tell any threads running serviceQueue to stop as soon as they're done
     // servicing whatever task they're currently servicing (drain=false) or when
     // there is no work left to be done (drain=true)
     void stop(bool drain = false);
 
     // Returns number of tasks waiting to be serviced, and first and last task
     // times
     size_t getQueueInfo(boost::chrono::system_clock::time_point &first,
                         boost::chrono::system_clock::time_point &last) const;
 
     // Returns true if there are threads actively running in serviceQueue()
     bool AreThreadsServicingQueue() const;
 
 private:
     std::multimap<boost::chrono::system_clock::time_point, Function> taskQueue;
     boost::condition_variable newTaskScheduled;
     mutable boost::mutex newTaskMutex;
     int nThreadsServicingQueue;
     bool stopRequested;
     bool stopWhenEmpty;
     bool shouldStop() const {
         return stopRequested || (stopWhenEmpty && taskQueue.empty());
     }
 };
 
 /**
  * Class used by CScheduler clients which may schedule multiple jobs
  * which are required to be run serially. Does not require such jobs
  * to be executed on the same thread, but no two jobs will be executed
  * at the same time.
  */
 class SingleThreadedSchedulerClient {
 private:
     CScheduler *m_pscheduler;
 
     CCriticalSection m_cs_callbacks_pending;
-    std::list<std::function<void(void)>> m_callbacks_pending;
-    bool m_are_callbacks_running = false;
+    std::list<std::function<void(void)>>
+        m_callbacks_pending GUARDED_BY(m_cs_callbacks_pending);
+    bool m_are_callbacks_running GUARDED_BY(m_cs_callbacks_pending) = false;
 
     void MaybeScheduleProcessQueue();
     void ProcessQueue();
 
 public:
     explicit SingleThreadedSchedulerClient(CScheduler *pschedulerIn)
         : m_pscheduler(pschedulerIn) {}
     void AddToProcessQueue(std::function<void(void)> func);
 
     // Processes all remaining queue members on the calling thread, blocking
     // until queue is empty
     // Must be called after the CScheduler has no remaining processing threads!
     void EmptyQueue();
 
     size_t CallbacksPending();
 };
 
 #endif