diff --git a/src/kernel/mconfig.ml b/src/kernel/mconfig.ml
index 77c0d9d95..5628a9b0e 100644
--- a/src/kernel/mconfig.ml
+++ b/src/kernel/mconfig.ml
@@ -838,3 +838,15 @@ let unitname t =
       | Some prefix -> prefix ^ basename
       | None -> basename
     end
+
+let intf_or_impl t =
+  let extension = Filename.extension t.query.filename in
+  try
+    List.find_map t.merlin.suffixes ~f:(fun (impl, intf) ->
+        if String.equal extension impl then Some Unit_info.Impl
+        else if String.equal extension intf then Some Unit_info.Intf
+        else None)
+  with Not_found -> Unit_info.Impl
+
+let unit_info t =
+  Unit_info.make ~source_file:t.query.filename (intf_or_impl t) (unitname t)
diff --git a/src/kernel/mconfig.mli b/src/kernel/mconfig.mli
index 1b4430b4a..525e0eaf6 100644
--- a/src/kernel/mconfig.mli
+++ b/src/kernel/mconfig.mli
@@ -129,3 +129,7 @@ val global_modules : ?include_current:bool -> t -> string list
 val filename : t -> string
 
 val unitname : t -> string
+
+val intf_or_impl : t -> Unit_info.intf_or_impl
+
+val unit_info : t -> Unit_info.t
diff --git a/src/kernel/mocaml.ml b/src/kernel/mocaml.ml
index 4f9fc0fa5..e40877bd2 100644
--- a/src/kernel/mocaml.ml
+++ b/src/kernel/mocaml.ml
@@ -35,7 +35,7 @@ let setup_reader_config config =
   let open Mconfig in
   let open Clflags in
   let ocaml = config.ocaml in
-  Env.set_unit_name (Mconfig.unitname config);
+  Env.set_current_unit (Mconfig.unit_info config);
   Location.input_name := config.query.filename;
   fast := ocaml.unsafe;
   classic := ocaml.classic;