diff --git a/include/sqlpp11/on.h b/include/sqlpp11/on.h
index 9c957dd9..79f2ab08 100644
--- a/include/sqlpp11/on.h
+++ b/include/sqlpp11/on.h
@@ -28,6 +28,7 @@
 #define SQLPP_ON_H
 
 #include <sqlpp11/type_traits.h>
+#include <sqlpp11/detail/set.h>
 #include <sqlpp11/vendor/interpret_tuple.h>
 #include <sqlpp11/vendor/interpretable_list.h>