diff --git a/include/flatbuffers/idl.h b/include/flatbuffers/idl.h
index 4e0bc3f69..272fd2cae 100644
--- a/include/flatbuffers/idl.h
+++ b/include/flatbuffers/idl.h
@@ -19,6 +19,7 @@
 
 #include <map>
 #include <memory>
+#include <functional>
 
 #include "flatbuffers/flatbuffers.h"