diff --git a/CLI11.hpp b/CLI11.hpp
index 5577a7e..bbc8dd8 100644
--- a/CLI11.hpp
+++ b/CLI11.hpp
@@ -4,6 +4,7 @@ used by this program.
 */
 
 #pragma once
+#include <algorithm>
 #include <functional>
 #include <iostream>
 #include <map>
@@ -392,4 +393,4 @@ public:
 namespace CLI {
 using App = ::App;
 using ParseError = ::ParseError;
-} // namespace CLI
\ No newline at end of file
+} // namespace CLI