diff --git a/io/exportthread.cpp b/io/exportthread.cpp
index 5e4f1a34e..f6b6dc134 100644
--- a/io/exportthread.cpp
+++ b/io/exportthread.cpp
@@ -489,5 +489,7 @@ void ExportThread::run() {
 }
 
 void ExportThread::wake() {
+    mutex.lock();
 	waitCond.wakeAll();
+    mutex.unlock();
 }