diff --git a/include/xlnt/cell/cell_reference.hpp b/include/xlnt/cell/cell_reference.hpp
index 66185f37..c8efcb4b 100644
--- a/include/xlnt/cell/cell_reference.hpp
+++ b/include/xlnt/cell/cell_reference.hpp
@@ -25,7 +25,9 @@
 
 #include <xlnt/xlnt_config.hpp>
 #include <xlnt/cell/index_types.hpp>
+
 #include <cstdint>
+#include <functional>
 #include <string>
 #include <tuple>
 #include <utility>