diff --git a/parsing/pprintast.ml b/parsing/pprintast.ml
index bf1fd14dd2aa..c6f48d16bffb 100644
--- a/parsing/pprintast.ml
+++ b/parsing/pprintast.ml
@@ -547,8 +547,8 @@ and expression ctxt f x =
                   then String.sub s 1 (String.length s -1)
                   else s in
                 begin match l with
-                | [(Nolabel, _) as v] ->
-                  pp f "@[<2>%s@;%a@]" s (label_x_expression_param ctxt) v
+                | [(Nolabel, x)] ->
+                  pp f "@[<2>%s@;%a@]" s (simple_expr ctxt) x
                 | _   ->
                   pp f "@[<2>%a %a@]" (simple_expr ctxt) e
                     (list (label_x_expression_param ctxt)) l
@@ -572,7 +572,7 @@ and expression ctxt f x =
          | _ -> assert false)
     | Pexp_setfield (e1, li, e2) ->
         pp f "@[<2>%a.%a@ <-@ %a@]"
-          (simple_expr ctxt) e1 longident_loc li (expression ctxt) e2
+          (simple_expr ctxt) e1 longident_loc li (simple_expr ctxt) e2
     | Pexp_ifthenelse (e1, e2, eo) ->
         (* @;@[<2>else@ %a@]@] *)
         let fmt:(_,_,_)format ="@[<hv0>@[<2>if@ %a@]@;@[<2>then@ %a@]%a@]" in
diff --git a/testsuite/tests/parsetree/source.ml b/testsuite/tests/parsetree/source.ml
index cbb96405456d..7742c5995e25 100644
--- a/testsuite/tests/parsetree/source.ml
+++ b/testsuite/tests/parsetree/source.ml
@@ -7263,3 +7263,14 @@ let foo : type a' b'. a' -> b' = fun a -> assert false
 let foo : type t' . t' = fun (type t') -> (assert false : t')
 let foo : 't . 't = fun (type t) -> (assert false : t)
 let foo : type a' b' c' t. a' -> b' -> c' -> t = fun a b c -> assert false
+
+let f x =
+  x.contents <- (print_string "coucou" ; x.contents)
+
+let ( ~$ ) x = Some x
+let g x =
+  ~$ (x.contents)
+
+let ( ~$ ) x y = (x, y)
+let g x y =
+  ~$ (x.contents) (y.contents)
diff --git a/testsuite/tests/parsetree/test.ml b/testsuite/tests/parsetree/test.ml
index ba8819dbba59..86ed3c8cc613 100644
--- a/testsuite/tests/parsetree/test.ml
+++ b/testsuite/tests/parsetree/test.ml
@@ -1,5 +1,11 @@
 (* (c) Alain Frisch / Lexifi *)
 (* cf. PR#7200 *)
+
+let diff =
+  match Array.to_list Sys.argv with
+  | [_; diff] -> diff
+  | _ -> "diff -u"
+
 let report_err exn =
   match exn with
     | Sys_error msg ->
@@ -69,7 +75,7 @@ let test parse_fun pprint print map filename =
             Printf.printf "%s:  FAIL, REPARSED AST IS DIFFERENT\n%!" filename;
             let f1 = to_tmp_file print ast in
             let f2 = to_tmp_file print ast2 in
-            let cmd = Printf.sprintf "diff -u %s %s"
+            let cmd = Printf.sprintf "%s %s %s" diff
                 (Filename.quote f1) (Filename.quote f2) in
             let _ret = Sys.command cmd in
             print_endline"====================================================="