diff --git a/gui/ice40/worker.cc b/gui/ice40/worker.cc
index a309f868..4b101e7e 100644
--- a/gui/ice40/worker.cc
+++ b/gui/ice40/worker.cc
@@ -61,6 +61,8 @@ TaskManager::TaskManager(Context *ctx) : toTerminate(false)
 
 TaskManager::~TaskManager()
 {
+    if (workerThread.isRunning()) 
+        terminate_thread();
     workerThread.quit();
     workerThread.wait();
 }