diff --git a/src_main/concurrent/piblockingdequeue.h b/src_main/concurrent/piblockingdequeue.h
index d7ed9f98..fb480f9a 100644
--- a/src_main/concurrent/piblockingdequeue.h
+++ b/src_main/concurrent/piblockingdequeue.h
@@ -119,13 +119,14 @@ public:
 	 * @param defaultVal value, which returns if the specified waiting time elapses before an element is available
 	 * @return the head of this queue, or defaultVal if the specified waiting time elapses before an element is available
 	 */
-	T poll(int timeoutMs, const T & defaultVal) {
+	T poll(int timeoutMs, const T & defaultVal, bool* isOk = nullptr) {
 		T t;
 		mutex.lock();
-		bool isOk = cond_var_add->waitFor(mutex, timeoutMs, [&]() { return !PIDeque<T>::isEmpty(); });
-		t = isOk ? T(PIDeque<T>::take_front()) : defaultVal;
+		bool isNotEmpty = cond_var_add->waitFor(mutex, timeoutMs, [&]() { return !PIDeque<T>::isEmpty(); });
+		t = isNotEmpty ? T(PIDeque<T>::take_front()) : defaultVal;
 		mutex.unlock();
-		if (isOk) cond_var_rem->notifyOne();
+		if (isNotEmpty) cond_var_rem->notifyOne();
+		if (isOk != nullptr) *isOk = isNotEmpty;
 		return t;
 	}