diff --git a/test/Aclock.h b/test/Aclock.h
index 73e3c70c3f943c098ddedf7808cce6105fb3100e..a79a9a21acc2e6a036f13bf0d0d8d10f79284746 100644
--- a/test/Aclock.h
+++ b/test/Aclock.h
@@ -20,6 +20,7 @@
 #include <TPolyLine.h>
 #include <TDatime.h>
 #include <TPoints.h>
+#include <TMath.h>
 
 
 class TPolygon : public TPolyLine {