diff --git a/src/blackmisc/worker.h b/src/blackmisc/worker.h
index aa81cef14..9f4bf5417 100644
--- a/src/blackmisc/worker.h
+++ b/src/blackmisc/worker.h
@@ -13,6 +13,7 @@
 #define BLACKMISC_WORKER_H
 
 #include <QThread>
+#include <QMutex>
 #include <functional>
 #include <atomic>