diff --git a/src/build_system.ml b/src/build_system.ml
index b7670c05..ee14c68e 100644
--- a/src/build_system.ml
+++ b/src/build_system.ml
@@ -124,13 +124,22 @@ module Exec_status = struct
     | Running         of Running.t
 end
 
-let rule_loc ~loc ~dir =
+let rule_loc ~file_tree ~loc ~dir =
   match loc with
   | Some loc -> loc
   | None ->
+    let dir = Path.drop_optional_build_context dir in
+    let fname =
+      if File_tree.file_exists file_tree dir "dune" then
+        "dune"
+      else if File_tree.file_exists file_tree dir "jbuild" then
+        "jbuild"
+      else
+        "_unknown_"
+    in
     Loc.in_file
       (Path.to_string
-         (Path.drop_optional_build_context (Path.relative dir "jbuild")))
+         (Path.drop_optional_build_context (Path.relative dir fname)))
 
 module Internal_rule = struct
   module Id : sig
@@ -172,7 +181,7 @@ module Internal_rule = struct
 
   let compare a b = Id.compare a.id b.id
 
-  let loc ~dir t = rule_loc ~dir ~loc:t.loc
+  let loc ~file_tree ~dir t  = rule_loc ~file_tree ~dir ~loc:t.loc
 end
 
 module File_kind = struct
@@ -514,7 +523,8 @@ let add_spec t fn spec ~copy_source =
   | Some (File_spec.T { rule; _ }) ->
     match copy_source, rule.mode with
     | true, (Standard | Not_a_rule_stanza) ->
-      Loc.warn (Internal_rule.loc rule ~dir:(Path.parent fn))
+      Loc.warn (Internal_rule.loc rule ~dir:(Path.parent fn)
+                  ~file_tree:t.file_tree)
         "File %s is both generated by a rule and present in the source tree.\n\
          As a result, the rule is currently ignored, however this will become an error \
          in the future.\n\
@@ -989,7 +999,9 @@ and load_dir_step2_exn t ~dir ~collector ~lazy_generators =
                 Pset.diff source_files_for_targtes absent_targets
               in
               Loc.fail
-                (rule_loc ~loc:rule.loc
+                (rule_loc
+                   ~file_tree:t.file_tree
+                   ~loc:rule.loc
                    ~dir:(Path.drop_optional_build_context dir))
                 "\
 Some of the targets of this fallback rule are present in the source tree,
diff --git a/src/jbuild_load.ml b/src/jbuild_load.ml
index caf1e240..6f75cb4e 100644
--- a/src/jbuild_load.ml
+++ b/src/jbuild_load.ml
@@ -12,6 +12,7 @@ let filter_stanzas ~ignore_promoted_rules stanzas =
 module Jbuilds = struct
   type script =
     { dir   : Path.t
+    ; file  : Path.t
     ; scope : Scope_info.t
     }
 
@@ -114,8 +115,7 @@ end
         | Literal x -> Left  x
         | Script  x -> Right x)
     in
-    Fiber.parallel_map dynamic ~f:(fun { dir; scope } ->
-      let file = Path.relative dir "jbuild" in
+    Fiber.parallel_map dynamic ~f:(fun { dir; file; scope } ->
       let generated_jbuild =
         Path.append (Path.relative generated_jbuilds_dir context.name) file
       in
@@ -207,15 +207,15 @@ module Sexp_io = struct
       loop0 Parser.Stack.empty 0)
 end
 
-let load ~dir ~scope ~ignore_promoted_rules =
-  let file = Path.relative dir "jbuild" in
+let load ~dir ~scope ~ignore_promoted_rules ~fname =
+  let file = Path.relative dir fname in
   match Sexp_io.load_many_or_ocaml_script file with
   | Sexps sexps ->
     Jbuilds.Literal (dir, scope,
                      Stanzas.parse scope sexps ~file
                      |> filter_stanzas ~ignore_promoted_rules)
   | Ocaml_script ->
-    Script { dir; scope }
+    Script { dir; scope; file }
 
 let load ?extra_ignored_subtrees ?(ignore_promoted_rules=false) () =
   let ftree = File_tree.load Path.root ?extra_ignored_subtrees in
@@ -303,8 +303,15 @@ let load ?extra_ignored_subtrees ?(ignore_promoted_rules=false) () =
       let sub_dirs = File_tree.Dir.sub_dirs dir in
       let scope = Option.value (Path.Map.find scopes path) ~default:scope in
       let jbuilds =
-        if String.Set.mem files "jbuild" then
-          let jbuild = load ~dir:path ~scope ~ignore_promoted_rules in
+        if String.Set.mem files "dune" then
+          let jbuild =
+            load ~dir:path ~scope ~ignore_promoted_rules ~fname:"dune"
+          in
+          jbuild :: jbuilds
+        else if String.Set.mem files "jbuild" then
+          let jbuild =
+            load ~dir:path ~scope ~ignore_promoted_rules ~fname:"jbuild"
+          in
           jbuild :: jbuilds
         else
           jbuilds
diff --git a/src/process.ml b/src/process.ml
index 5b2f52ed..f1d8bace 100644
--- a/src/process.ml
+++ b/src/process.ml
@@ -237,7 +237,7 @@ let run_internal ?dir ?(stdout_to=Terminal) ?(stderr_to=Terminal) ~env ~purpose
   let output_filename, stdout_fd, stderr_fd, to_close =
     match stdout_to, stderr_to with
     | (Terminal, _ | _, Terminal) when !Clflags.capture_outputs ->
-      let fn = Temp.create "jbuilder" ".output" in
+      let fn = Temp.create "dune" ".output" in
       let fd = Unix.openfile (Path.to_string fn) [O_WRONLY; O_SHARE_DELETE] 0 in
       (Some fn, fd, fd, Some fd)
     | _ ->
@@ -329,7 +329,7 @@ let run ?dir ?stdout_to ?stderr_to ~env ?(purpose=Internal_job) fail_mode
     ~f:ignore
 
 let run_capture_gen ?dir ~env ?(purpose=Internal_job) fail_mode prog args ~f =
-  let fn = Temp.create "jbuild" ".output" in
+  let fn = Temp.create "dune" ".output" in
   map_result fail_mode
     (run_internal ?dir ~stdout_to:(File fn)
        ~env ~purpose fail_mode prog args)