diff --git a/include/tclap/XorHandler.h b/include/tclap/XorHandler.h
index d1f4121..9e566ed 100644
--- a/include/tclap/XorHandler.h
+++ b/include/tclap/XorHandler.h
@@ -25,6 +25,7 @@
 #include <tclap/Arg.h>
 #include <string>
 #include <vector>
+#include <algorithm>
 
 using namespace std;