diff --git a/src/exe.ml b/src/exe.ml
index 33541366..221d731a 100644
--- a/src/exe.ml
+++ b/src/exe.ml
@@ -191,7 +191,8 @@ let build_and_link_many
   Module_compilation.build_modules sctx
     ~js_of_ocaml
     ~dynlink:true ~flags ~scope ~dir ~obj_dir ~dep_graphs ~modules
-    ~requires ~alias_module:None;
+    ~alias_module:None
+    ~includes:(Module_compilation.Includes.make sctx ~requires);
 
   List.iter programs ~f:(fun { Program.name; main_module_name } ->
     let top_sorted_modules =
diff --git a/src/gen_rules.ml b/src/gen_rules.ml
index 51a7d504..45a107a8 100644
--- a/src/gen_rules.ml
+++ b/src/gen_rules.ml
@@ -606,7 +606,8 @@ module Gen(P : Install_rules.Params) = struct
     let js_of_ocaml = lib.buildable.js_of_ocaml in
     Module_compilation.build_modules sctx
       ~js_of_ocaml ~dynlink ~flags ~scope ~dir ~obj_dir ~dep_graphs
-      ~modules ~requires ~alias_module;
+      ~modules ~alias_module
+      ~includes:(Module_compilation.Includes.make sctx ~requires);
     Option.iter alias_module ~f:(fun m ->
       let flags = Ocaml_flags.default ~profile:(SC.profile sctx) in
       Module_compilation.build_module sctx m
@@ -618,7 +619,7 @@ module Gen(P : Install_rules.Params) = struct
         ~dir
         ~obj_dir
         ~dep_graphs:(Ocamldep.Dep_graphs.dummy m)
-        ~includes:(Cm_kind.Dict.make_all (Arg_spec.As []))
+        ~includes:Module_compilation.Includes.empty
         ~alias_module:None);
 
     if Library.has_stubs lib then begin
diff --git a/src/module_compilation.ml b/src/module_compilation.ml
index 399ef1e6..1c0bc190 100644
--- a/src/module_compilation.ml
+++ b/src/module_compilation.ml
@@ -4,6 +4,37 @@ open! No_io
 
 module SC = Super_context
 
+module Includes = struct
+  type t = string list Arg_spec.t Cm_kind.Dict.t
+
+  let make sctx ~requires : _ Cm_kind.Dict.t =
+    match requires with
+    | Error exn -> Cm_kind.Dict.make_all (Arg_spec.Dyn (fun _ -> raise exn))
+    | Ok libs ->
+      let iflags =
+        Lib.L.include_flags libs ~stdlib_dir:(SC.context sctx).stdlib_dir
+      in
+      let cmi_includes =
+        Arg_spec.S [ iflags
+                   ; Hidden_deps
+                       (SC.Libs.file_deps sctx libs ~ext:".cmi")
+                   ]
+      in
+      let cmi_and_cmx_includes =
+        Arg_spec.S [ iflags
+                   ; Hidden_deps
+                       (SC.Libs.file_deps sctx libs ~ext:".cmi-and-.cmx")
+                   ]
+      in
+      { cmi = cmi_includes
+      ; cmo = cmi_includes
+      ; cmx = cmi_and_cmx_includes
+      }
+
+  let empty =
+    Cm_kind.Dict.make_all (Arg_spec.As [])
+end
+
 module Target : sig
   type t
   val cm : Module.t -> Cm_kind.t -> t
@@ -107,47 +138,24 @@ let build_cm sctx ?sandbox ~dynlink ~flags ~cm_kind ~dep_graphs
            ; Hidden_targets hidden_targets
            ])))
 
-let build_module sctx ?sandbox ~dynlink ~js_of_ocaml ~flags m ~scope ~dir
+let build_module sctx ?sandbox ~dynlink ?js_of_ocaml ~flags m ~scope ~dir
       ~obj_dir ~dep_graphs ~includes ~alias_module =
   List.iter Cm_kind.all ~f:(fun cm_kind ->
     let includes = Cm_kind.Dict.get includes cm_kind in
     build_cm sctx ?sandbox ~dynlink ~flags ~dir ~obj_dir ~dep_graphs m ~cm_kind
       ~includes ~alias_module);
-  (* Build *.cmo.js *)
-  let src = Module.cm_file_unsafe m ~obj_dir Cm_kind.Cmo in
-  let target =
-    Path.extend_basename (Module.cm_file_unsafe m ~obj_dir:dir Cm_kind.Cmo)
-      ~suffix:".js"
-  in
-  SC.add_rules sctx
-    (Js_of_ocaml_rules.build_cm sctx ~scope ~dir ~js_of_ocaml ~src ~target)
+  Option.iter js_of_ocaml ~f:(fun js_of_ocaml ->
+    (* Build *.cmo.js *)
+    let src = Module.cm_file_unsafe m ~obj_dir Cm_kind.Cmo in
+    let target =
+      Path.extend_basename (Module.cm_file_unsafe m ~obj_dir:dir Cm_kind.Cmo)
+        ~suffix:".js"
+    in
+    SC.add_rules sctx
+      (Js_of_ocaml_rules.build_cm sctx ~scope ~dir ~js_of_ocaml ~src ~target))
 
 let build_modules sctx ~dynlink ~js_of_ocaml ~flags ~scope ~dir ~obj_dir
-      ~dep_graphs ~modules ~requires ~alias_module =
-  let includes : _ Cm_kind.Dict.t =
-    match requires with
-    | Error exn -> Cm_kind.Dict.make_all (Arg_spec.Dyn (fun _ -> raise exn))
-    | Ok libs ->
-      let iflags =
-        Lib.L.include_flags libs ~stdlib_dir:(SC.context sctx).stdlib_dir
-      in
-      let cmi_includes =
-        Arg_spec.S [ iflags
-                   ; Hidden_deps
-                       (SC.Libs.file_deps sctx libs ~ext:".cmi")
-                   ]
-      in
-      let cmi_and_cmx_includes =
-        Arg_spec.S [ iflags
-                   ; Hidden_deps
-                       (SC.Libs.file_deps sctx libs ~ext:".cmi-and-.cmx")
-                   ]
-      in
-      { cmi = cmi_includes
-      ; cmo = cmi_includes
-      ; cmx = cmi_and_cmx_includes
-      }
-  in
+      ~dep_graphs ~modules ~includes ~alias_module =
   Module.Name.Map.iter
     (match alias_module with
      | None -> modules
diff --git a/src/module_compilation.mli b/src/module_compilation.mli
index 172fb92e..e25a603f 100644
--- a/src/module_compilation.mli
+++ b/src/module_compilation.mli
@@ -2,19 +2,28 @@
 
 open Import
 
+module Includes : sig
+  type t
+
+  val make : Super_context.t -> requires:Lib.t list Or_exn.t -> t
+
+  (** Empty set of include directories *)
+  val empty : t
+end
+
 (** Setup rules to build a single module. *)
 val build_module
   :  Super_context.t
   -> ?sandbox:bool
   -> dynlink:bool
-  -> js_of_ocaml:Jbuild.Js_of_ocaml.t
+  -> ?js_of_ocaml:Jbuild.Js_of_ocaml.t
   -> flags:Ocaml_flags.t
   -> Module.t
   -> scope:Scope.t
   -> dir:Path.t
   -> obj_dir:Path.t
   -> dep_graphs:Ocamldep.Dep_graphs.t
-  -> includes:string list Arg_spec.t Cm_kind.Dict.t
+  -> includes:Includes.t
   -> alias_module:Module.t option
   -> unit
 
@@ -29,6 +38,6 @@ val build_modules
   -> obj_dir:Path.t
   -> dep_graphs:Ocamldep.Dep_graphs.t
   -> modules:Module.t Module.Name.Map.t
-  -> requires:Lib.t list Or_exn.t
+  -> includes:Includes.t
   -> alias_module:Module.t option
   -> unit