diff --git a/casbin/enforcer_interface.h b/casbin/enforcer_interface.h
index d838bf69..4dc0803d 100644
--- a/casbin/enforcer_interface.h
+++ b/casbin/enforcer_interface.h
@@ -17,6 +17,7 @@
 #ifndef CASBIN_CPP_ENFORCER_INTERFACE
 #define CASBIN_CPP_ENFORCER_INTERFACE
 
+#include "./data_types.h"
 #include "./model/model.h"
 #include "./persist/adapter.h"
 #include "./persist/default_watcher.h"
@@ -151,4 +152,4 @@ class IEnforcer {
 
 } // namespace casbin
 
-#endif
\ No newline at end of file
+#endif