diff --git a/test/stressEntryList.cxx b/test/stressEntryList.cxx
index e39a80b..ee6303b 100644
--- a/test/stressEntryList.cxx
+++ b/test/stressEntryList.cxx
@@ -38,6 +38,7 @@
 #include <map>
 #include <list>
 #include <array>
+#include <functional>
 #include <stdlib.h>
 #include "TApplication.h"
 #include "TEntryList.h"