diff --git a/panda/src/express/clockObject.h b/panda/src/express/clockObject.h
index 39a12211b9..b9b73cb00a 100644
--- a/panda/src/express/clockObject.h
+++ b/panda/src/express/clockObject.h
@@ -28,6 +28,7 @@
 #include "cycleDataWriter.h"
 #include "cycleDataStageReader.h"
 #include "pipelineCycler.h"
+#include "thread.h"
 
 class EXPCL_PANDAEXPRESS TimeVal {
 PUBLISHED: