diff --git a/src/engine/workPool.cpp b/src/engine/workPool.cpp
index fd1993aa1..005645ee5 100644
--- a/src/engine/workPool.cpp
+++ b/src/engine/workPool.cpp
@@ -141,7 +141,7 @@ void DivWorkPool::wait() {
 
   // start running
   for (unsigned int i=0; i<count; i++) {
-    if (!workThreads[i].promiseAlreadySet) {
+    if (!workThreads[i].promiseAlreadySet && !workThreads[i].tasks.empty()) {
       try {
         workThreads[i].lock.lock();
         workThreads[i].promiseAlreadySet=true;