diff --git a/src/migrate_411_412.ml b/src/migrate_411_412.ml
index 2117dfbb..61de351d 100644
--- a/src/migrate_411_412.ml
+++ b/src/migrate_411_412.ml
@@ -1,3 +1,4 @@
+open Stdlib0
 module From = Ast_411
 module To = Ast_412
 let rec copy_toplevel_phrase :
diff --git a/src/migrate_412_411.ml b/src/migrate_412_411.ml
index 9e3cc5d6..c0ed630d 100644
--- a/src/migrate_412_411.ml
+++ b/src/migrate_412_411.ml
@@ -1,3 +1,4 @@
+open Stdlib0
 module From = Ast_412
 module To = Ast_411
 let rec copy_toplevel_phrase :