diff --git a/src/test/csf/Tx.h b/src/test/csf/Tx.h
index b21481dcb..f87f38216 100644
--- a/src/test/csf/Tx.h
+++ b/src/test/csf/Tx.h
@@ -22,6 +22,7 @@
 #include <xrpl/beast/hash/uhash.h>
 #include <boost/container/flat_set.hpp>
 #include <boost/iterator/function_output_iterator.hpp>
+#include <algorithm>
 #include <map>
 #include <ostream>
 #include <sstream>