diff --git a/sledge/src/reg.mli b/sledge/src/reg.mli
index 568b21b70..b5569d163 100644
--- a/sledge/src/reg.mli
+++ b/sledge/src/reg.mli
@@ -7,4 +7,4 @@
 
 (** Variables *)
 
-include module type of Exp.Reg
+include module type of struct include Exp.Reg end