diff --git a/core/parallel.cpp b/core/parallel.cpp
index 0a2568b..e7d79f6 100644
--- a/core/parallel.cpp
+++ b/core/parallel.cpp
@@ -23,7 +23,9 @@ class Parallel
 
         // wait for workers to finish task to make sure they're ready
         m_workers_active = m_workers.size();
-        m_signal_done.wait(ul);
+        while (m_workers_active) {
+            m_signal_done.wait(ul);
+        }
     }
 
     ~Parallel() {