diff --git a/utils/LocTimer.cpp b/utils/LocTimer.cpp
index e1be1e8a..277a8135 100644
--- a/utils/LocTimer.cpp
+++ b/utils/LocTimer.cpp
@@ -539,22 +539,38 @@ bool LocTimer::stop() {
 class LocTimerWrapper : public LocTimer {
     loc_timer_callback mCb;
     void* mCallerData;
+    static pthread_mutex_t mMutex;
+    inline ~LocTimerWrapper() { mCb = NULL; }
 public:
     inline LocTimerWrapper(loc_timer_callback cb, void* callerData) :
         mCb(cb), mCallerData(callerData) {}
+    inline bool isAlive() { return mCb != NULL; }
+    void destroy() {
+        pthread_mutex_lock(&mMutex);
+        if (isAlive()) {
+            delete this;
+        }
+        pthread_mutex_unlock(&mMutex);
+    }
     inline virtual void timeOutCallback() {
         mCb(mCallerData, 0);
-        delete this;
+        destroy();
     }
 };
 
+pthread_mutex_t LocTimerWrapper::mMutex = PTHREAD_MUTEX_INITIALIZER;
+
 void* loc_timer_start(uint64_t msec, loc_timer_callback cb_func,
                       void *caller_data, bool wake_on_expire)
 {
-    LocTimerWrapper* locTimerWrapper = new LocTimerWrapper(cb_func, caller_data);
+    LocTimerWrapper* locTimerWrapper = NULL;
 
-    if (locTimerWrapper) {
-        locTimerWrapper->start(msec, wake_on_expire);
+    if (cb_func) {
+        locTimerWrapper = new LocTimerWrapper(cb_func, caller_data);
+
+        if (locTimerWrapper) {
+            locTimerWrapper->start(msec, wake_on_expire);
+        }
     }
 
     return locTimerWrapper;
@@ -565,7 +581,7 @@ void loc_timer_stop(void*&  handle)
     if (handle) {
         LocTimerWrapper* locTimerWrapper = (LocTimerWrapper*)(handle);
         locTimerWrapper->stop();
-        delete locTimerWrapper;
+        locTimerWrapper->destroy();
         handle = NULL;
     }
 }
diff --git a/utils/loc_timer.h b/utils/loc_timer.h
index 8836d1ea..2967858e 100644
--- a/utils/loc_timer.h
+++ b/utils/loc_timer.h
@@ -45,7 +45,8 @@ typedef void (*loc_timer_callback)(void *user_data, int32_t result);
 
 /*
     delay_msec:         timeout value for the timer.
-    loc_timer_callback: callback function pointer, implemented by client.
+    cb_func:            callback function pointer, implemented by client.
+                        Can not be NULL.
     user_data:          client context pointer, passthrough.  Will be
                         returned when loc_timer_callback() is called.
     wakeOnExpire:       true if to wake up CPU (if sleeping) upon timer
@@ -53,9 +54,10 @@ typedef void (*loc_timer_callback)(void *user_data, int32_t result);
                         false if to wait until next time CPU wakes up (if
                                  sleeping) and then notify the client.
     Returns the handle, which can be used to stop the timer
+                        NULL, if timer start fails (e.g. if cb_func is NULL).
 */
 void* loc_timer_start(uint64_t delay_msec,
-                      loc_timer_callback,
+                      loc_timer_callback cb_func,
                       void *user_data,
                       bool wake_on_expire=false);