diff --git a/source/detail/xlsx_consumer.hpp b/source/detail/xlsx_consumer.hpp
index e0531127..45dacedd 100644
--- a/source/detail/xlsx_consumer.hpp
+++ b/source/detail/xlsx_consumer.hpp
@@ -24,6 +24,7 @@
 #pragma once
 
 #include <cstdint>
+#include <functional>
 #include <iostream>
 #include <memory>
 #include <unordered_map>