diff --git a/test/s3_unit_tests.cc b/test/s3_unit_tests.cc
index 0922997..9ef555f 100644
--- a/test/s3_unit_tests.cc
+++ b/test/s3_unit_tests.cc
@@ -30,6 +30,7 @@
 #include <XrdSys/XrdSysError.hh>
 #include <gtest/gtest.h>
 
+#include <algorithm>
 #include <fcntl.h>
 #include <fstream>
 #include <iostream>