diff --git a/CHANGES.md b/CHANGES.md
index 4ca871543b..6c083c1da5 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -85,6 +85,10 @@ profile. This started with version 0.26.0.
   end
   ```
 
+- \* Allow `begin end` on one line in most cases. (#2745, @EmileTrotignon).
+  `f begin fun x -> y end` is not supported for now and is still always
+  multiline.
+
 ## 0.28.1
 
 ### Highlight
diff --git a/lib/Fmt_ast.ml b/lib/Fmt_ast.ml
index bfcece6d41..9131d792f9 100644
--- a/lib/Fmt_ast.ml
+++ b/lib/Fmt_ast.ml
@@ -3051,10 +3051,9 @@ and fmt_lazy c ~ctx ?(pro = noop) ~fmt_atrs ~infix_ext_attrs ~parens e =
 and fmt_beginend c ~loc ?(box = true) ?(pro = noop) ~ctx ~ctx0 ~fmt_atrs
     ~infix_ext_attrs ~indent_wrap ?eol e =
   let cmts_before = Cmts.fmt_before c ?eol loc in
-  let begin_ = fmt_infix_ext_attrs c ~pro:(str "begin") infix_ext_attrs
-  and end_ =
-    (if not box then break 1000 (-2) else break 1000 0)
-    $ str "end" $ fmt_atrs
+  let begin_ = fmt_infix_ext_attrs c ~pro:(str "begin") infix_ext_attrs in
+  let end_ =
+    (if not box then break 1000 (-2) else break 1 0) $ str "end" $ fmt_atrs
   in
   let box_beginend_sb = Params.Exp.box_beginend_subexpr c.conf ~ctx ~ctx0 in
   let beginend_box =
diff --git a/test/passing/refs.ahrefs/attributes.ml.ref b/test/passing/refs.ahrefs/attributes.ml.ref
index 0529fd5486..69a7fb2b72 100644
--- a/test/passing/refs.ahrefs/attributes.ml.ref
+++ b/test/passing/refs.ahrefs/attributes.ml.ref
@@ -576,11 +576,7 @@ let _ =
 
 let _ = ((module[@a] X) [@b])
 
-let _ =
-  begin[@a]
-    x
-  end
-  [@b]
+let _ = begin[@a] x end [@b]
 
 let fold input ~init ~f =
   foldi input ~init ~f:(fun (_ : int) acc x -> f acc x) [@nontail]
diff --git a/test/passing/refs.ahrefs/exp_grouping-parens.ml.ref b/test/passing/refs.ahrefs/exp_grouping-parens.ml.ref
index 347b3fffd7..38576e4068 100644
--- a/test/passing/refs.ahrefs/exp_grouping-parens.ml.ref
+++ b/test/passing/refs.ahrefs/exp_grouping-parens.ml.ref
@@ -283,19 +283,10 @@ let _ = begin%ext end
 let _ = begin%ext end (* foo *)
 let _ = x y
 let _ = (* foo *) x y
-let _ =
-  begin%ext
-    x y
-  end
-let _ =
-  begin%ext
-    (* foo *) x y
-  end
+let _ = begin%ext x y end
+let _ = begin%ext (* foo *) x y end
 
-let _ =
-  begin[@landmark "parse_constant_dividends"]
-    market_data_items := ()
-  end
+let _ = begin[@landmark "parse_constant_dividends"] market_data_items := () end
 
 let () = if a then b (* asd *)
 
@@ -531,11 +522,7 @@ let main =
   | A -> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
   | B -> bbbbbbbbbbbbbbbbbbbbbb
 
-let _ =
-  begin
-    a
-  end
-  [@a]
+let _ = begin a end [@a]
 
 let () =
   fooooo
diff --git a/test/passing/refs.ahrefs/exp_grouping.ml.ref b/test/passing/refs.ahrefs/exp_grouping.ml.ref
index 45d49cd420..4f3790ebaa 100644
--- a/test/passing/refs.ahrefs/exp_grouping.ml.ref
+++ b/test/passing/refs.ahrefs/exp_grouping.ml.ref
@@ -316,27 +316,12 @@ let _ = begin end
 let _ = begin end (* foo *)
 let _ = begin%ext end
 let _ = begin%ext end (* foo *)
-let _ =
-  begin
-    x y
-  end
-let _ =
-  begin
-    (* foo *) x y
-  end
-let _ =
-  begin%ext
-    x y
-  end
-let _ =
-  begin%ext
-    (* foo *) x y
-  end
+let _ = begin x y end
+let _ = begin (* foo *) x y end
+let _ = begin%ext x y end
+let _ = begin%ext (* foo *) x y end
 
-let _ =
-  begin[@landmark "parse_constant_dividends"]
-    market_data_items := ()
-  end
+let _ = begin[@landmark "parse_constant_dividends"] market_data_items := () end
 
 let () =
   if a then begin
@@ -611,11 +596,7 @@ let main =
   | A -> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
   | B -> bbbbbbbbbbbbbbbbbbbbbb
 
-let _ =
-  begin
-    a
-  end
-  [@a]
+let _ = begin a end [@a]
 
 let () =
   fooooo
diff --git a/test/passing/refs.ahrefs/extensions_exp_grouping.ml.ref b/test/passing/refs.ahrefs/extensions_exp_grouping.ml.ref
index 0b3b4aabdc..4d40c470ff 100644
--- a/test/passing/refs.ahrefs/extensions_exp_grouping.ml.ref
+++ b/test/passing/refs.ahrefs/extensions_exp_grouping.ml.ref
@@ -1,34 +1,9 @@
-let _ =
-  begin%ext
-    y >>= z
-  end
-let _ =
-  [%ext
-    begin
-      y >>= z
-    end]
-let _ =
-  x
-  >>= begin%ext
-    y >>= z
-  end
-let _ =
-  x
-  >>= [%ext
-        begin
-          y >>= z
-        end]
-let _ =
-  f
-    begin%ext
-      y >>= z
-    end
-let _ =
-  f
-    [%ext
-      begin
-        y >>= z
-      end]
+let _ = begin%ext y >>= z end
+let _ = [%ext begin y >>= z end]
+let _ = x >>= begin%ext y >>= z end
+let _ = x >>= [%ext begin y >>= z end]
+let _ = f begin%ext y >>= z end
+let _ = f [%ext begin y >>= z end]
 
 let _ = (module%ext S)
 let _ = [%ext (module S)]
diff --git a/test/passing/refs.ahrefs/reformat_string.ml.ref b/test/passing/refs.ahrefs/reformat_string.ml.ref
index 3d5cac7f74..77120fcff9 100644
--- a/test/passing/refs.ahrefs/reformat_string.ml.ref
+++ b/test/passing/refs.ahrefs/reformat_string.ml.ref
@@ -6,15 +6,9 @@ let _ = (* test *) "asd"
 
 let _ = "asd"
 
-let _ =
-  begin
-    (* te""st *) "asd"
-  end
-
-let _ =
-  begin
-    "asd"
-  end
+let _ = begin (* te""st *) "asd" end
+
+let _ = begin "asd" end
 
 let _ = 'a'
 
diff --git a/test/passing/refs.ahrefs/source.ml.err b/test/passing/refs.ahrefs/source.ml.err
index 1269cc4736..da3c73773e 100644
--- a/test/passing/refs.ahrefs/source.ml.err
+++ b/test/passing/refs.ahrefs/source.ml.err
@@ -1,4 +1,4 @@
-Warning: source.ml:3417 exceeds the margin
-Warning: source.ml:6551 exceeds the margin
-Warning: source.ml:6985 exceeds the margin
-Warning: source.ml:7817 exceeds the margin
+Warning: source.ml:3415 exceeds the margin
+Warning: source.ml:6549 exceeds the margin
+Warning: source.ml:6983 exceeds the margin
+Warning: source.ml:7815 exceeds the margin
diff --git a/test/passing/refs.ahrefs/source.ml.ref b/test/passing/refs.ahrefs/source.ml.ref
index 11dc288f8e..2e387c954c 100644
--- a/test/passing/refs.ahrefs/source.ml.ref
+++ b/test/passing/refs.ahrefs/source.ml.ref
@@ -96,9 +96,7 @@ let () =
   assert%foo[@foo] true;
   lazy%foo[@foo] x;
   object%foo[@foo] end;
-  begin%foo[@foo]
-    3
-  end;
+  begin%foo[@foo] 3 end;
   new%foo[@foo] x;
 
   match%foo[@foo] () with
diff --git a/test/passing/refs.default/attributes.ml.ref b/test/passing/refs.default/attributes.ml.ref
index df28db0a04..79de991ee8 100644
--- a/test/passing/refs.default/attributes.ml.ref
+++ b/test/passing/refs.default/attributes.ml.ref
@@ -454,12 +454,7 @@ let _ =
   [@b]
 
 let _ = ((module[@a] X) [@b])
-
-let _ =
-  begin[@a]
-    x
-  end
-  [@b]
+let _ = begin[@a] x end [@b]
 
 let fold input ~init ~f =
   foldi input ~init ~f:(fun (_ : int) acc x -> f acc x) [@nontail]
diff --git a/test/passing/refs.default/cases_exp_grouping.ml.ref b/test/passing/refs.default/cases_exp_grouping.ml.ref
index 1153a6b1f8..6f431aa001 100644
--- a/test/passing/refs.default/cases_exp_grouping.ml.ref
+++ b/test/passing/refs.default/cases_exp_grouping.ml.ref
@@ -116,9 +116,7 @@ let a =
   | B -> bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
   end
 
-let a =
-  begin match f x i with A -> a | B -> b
-  end
+let a = begin match f x i with A -> a | B -> b end
 
 let a =
   begin[@a] match[@b]
@@ -177,9 +175,7 @@ let a =
   | B -> bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
   end
 
-let a =
-  begin try f x i with A -> a | B -> b
-  end
+let a = begin try f x i with A -> a | B -> b end
 
 let a =
   begin[@a] try[@b]
diff --git a/test/passing/refs.default/exp_grouping-parens.ml.ref b/test/passing/refs.default/exp_grouping-parens.ml.ref
index 153fb6f88d..3fb25ea36c 100644
--- a/test/passing/refs.default/exp_grouping-parens.ml.ref
+++ b/test/passing/refs.default/exp_grouping-parens.ml.ref
@@ -301,22 +301,9 @@ let _ = begin%ext end
 let _ = begin%ext end (* foo *)
 let _ = x y
 let _ = (* foo *) x y
-
-let _ =
-  begin%ext
-    x y
-  end
-
-let _ =
-  begin%ext
-    (* foo *) x y
-  end
-
-let _ =
-  begin[@landmark "parse_constant_dividends"]
-    market_data_items := ()
-  end
-
+let _ = begin%ext x y end
+let _ = begin%ext (* foo *) x y end
+let _ = begin[@landmark "parse_constant_dividends"] market_data_items := () end
 let () = if a then b (* asd *)
 
 let x =
@@ -548,11 +535,7 @@ let main =
   | A -> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
   | B -> bbbbbbbbbbbbbbbbbbbbbb
 
-let _ =
-  begin
-    a
-  end
-  [@a]
+let _ = begin a end [@a]
 
 let () =
   fooooo
diff --git a/test/passing/refs.default/exp_grouping.ml.ref b/test/passing/refs.default/exp_grouping.ml.ref
index c4a1afb6e9..2dbcccb813 100644
--- a/test/passing/refs.default/exp_grouping.ml.ref
+++ b/test/passing/refs.default/exp_grouping.ml.ref
@@ -332,31 +332,11 @@ let _ = begin end
 let _ = begin end (* foo *)
 let _ = begin%ext end
 let _ = begin%ext end (* foo *)
-
-let _ =
-  begin
-    x y
-  end
-
-let _ =
-  begin
-    (* foo *) x y
-  end
-
-let _ =
-  begin%ext
-    x y
-  end
-
-let _ =
-  begin%ext
-    (* foo *) x y
-  end
-
-let _ =
-  begin[@landmark "parse_constant_dividends"]
-    market_data_items := ()
-  end
+let _ = begin x y end
+let _ = begin (* foo *) x y end
+let _ = begin%ext x y end
+let _ = begin%ext (* foo *) x y end
+let _ = begin[@landmark "parse_constant_dividends"] market_data_items := () end
 
 let () =
   if a then begin
@@ -629,11 +609,7 @@ let main =
   | A -> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
   | B -> bbbbbbbbbbbbbbbbbbbbbb
 
-let _ =
-  begin
-    a
-  end
-  [@a]
+let _ = begin a end [@a]
 
 let () =
   fooooo
diff --git a/test/passing/refs.default/extensions_exp_grouping.ml.ref b/test/passing/refs.default/extensions_exp_grouping.ml.ref
index a18eb3ba9a..c25c206552 100644
--- a/test/passing/refs.default/extensions_exp_grouping.ml.ref
+++ b/test/passing/refs.default/extensions_exp_grouping.ml.ref
@@ -1,40 +1,9 @@
-let _ =
-  begin%ext
-    y >>= z
-  end
-
-let _ =
-  [%ext
-    begin
-      y >>= z
-    end]
-
-let _ =
-  x
-  >>= begin%ext
-    y >>= z
-  end
-
-let _ =
-  x
-  >>= [%ext
-        begin
-          y >>= z
-        end]
-
-let _ =
-  f
-    begin%ext
-      y >>= z
-    end
-
-let _ =
-  f
-    [%ext
-      begin
-        y >>= z
-      end]
-
+let _ = begin%ext y >>= z end
+let _ = [%ext begin y >>= z end]
+let _ = x >>= begin%ext y >>= z end
+let _ = x >>= [%ext begin y >>= z end]
+let _ = f begin%ext y >>= z end
+let _ = f [%ext begin y >>= z end]
 let _ = (module%ext S)
 let _ = [%ext (module S)]
 let _ = f (module%ext S)
diff --git a/test/passing/refs.default/js_begin.ml.ref b/test/passing/refs.default/js_begin.ml.ref
index 36e2430e79..09f5966762 100644
--- a/test/passing/refs.default/js_begin.ml.ref
+++ b/test/passing/refs.default/js_begin.ml.ref
@@ -9,6 +9,4 @@ let g = function
       foo;
       bar
 
-let () =
-  begin match foo with Bar -> snoo
-  end
+let () = begin match foo with Bar -> snoo end
diff --git a/test/passing/refs.default/js_pattern.ml.ref b/test/passing/refs.default/js_pattern.ml.ref
index 31b486bc70..f366b55fa8 100644
--- a/test/passing/refs.default/js_pattern.ml.ref
+++ b/test/passing/refs.default/js_pattern.ml.ref
@@ -2,10 +2,7 @@ let f = function _ -> 0
 let f x = match x with _ -> 0
 let f = function _ -> 0
 let f x = match x with _ -> 0
-
-let f x =
-  begin match x with _ -> 0
-  end
+let f x = begin match x with _ -> 0 end
 
 let check_price t = function
   | { Exec.trade_at_settlement = None | Some false } -> ()
diff --git a/test/passing/refs.default/reformat_string.ml.ref b/test/passing/refs.default/reformat_string.ml.ref
index 8a4c2d022b..843e62365e 100644
--- a/test/passing/refs.default/reformat_string.ml.ref
+++ b/test/passing/refs.default/reformat_string.ml.ref
@@ -2,17 +2,8 @@ let _ = 'a'
 let _ = 'a'
 let _ = (* test *) "asd"
 let _ = "asd"
-
-let _ =
-  begin
-    (* te""st *) "asd"
-  end
-
-let _ =
-  begin
-    "asd"
-  end
-
+let _ = begin (* te""st *) "asd" end
+let _ = begin "asd" end
 let _ = 'a'
 let _ = 'a'
 let _ = function 'a' .. 'z' -> ()
diff --git a/test/passing/refs.default/source.ml.err b/test/passing/refs.default/source.ml.err
index 6e017154b8..1c673e9eb2 100644
--- a/test/passing/refs.default/source.ml.err
+++ b/test/passing/refs.default/source.ml.err
@@ -1,4 +1,4 @@
-Warning: source.ml:917 exceeds the margin
-Warning: source.ml:992 exceeds the margin
-Warning: source.ml:6638 exceeds the margin
-Warning: source.ml:7097 exceeds the margin
+Warning: source.ml:915 exceeds the margin
+Warning: source.ml:990 exceeds the margin
+Warning: source.ml:6636 exceeds the margin
+Warning: source.ml:7095 exceeds the margin
diff --git a/test/passing/refs.default/source.ml.ref b/test/passing/refs.default/source.ml.ref
index c14b59ab35..6afd4eb839 100644
--- a/test/passing/refs.default/source.ml.ref
+++ b/test/passing/refs.default/source.ml.ref
@@ -98,9 +98,7 @@ let () =
   assert%foo[@foo] true;
   lazy%foo[@foo] x;
   object%foo[@foo] end;
-  begin%foo[@foo]
-    3
-  end;
+  begin%foo[@foo] 3 end;
   new%foo[@foo] x;
 
   match%foo[@foo] () with
diff --git a/test/passing/refs.janestreet/attributes.ml.ref b/test/passing/refs.janestreet/attributes.ml.ref
index d6b46bebe3..03520185dc 100644
--- a/test/passing/refs.janestreet/attributes.ml.ref
+++ b/test/passing/refs.janestreet/attributes.ml.ref
@@ -526,14 +526,7 @@ let _ =
 ;;
 
 let _ = ((module[@a] X) [@b])
-
-let _ =
-  begin[@a]
-    x
-  end
-  [@b]
-;;
-
+let _ = begin[@a] x end [@b]
 let fold input ~init ~f = foldi input ~init ~f:(fun (_ : int) acc x -> f acc x) [@nontail]
 
 [@@@effect]
diff --git a/test/passing/refs.janestreet/exp_grouping-parens.ml.ref b/test/passing/refs.janestreet/exp_grouping-parens.ml.ref
index a221769b6a..30d0bf06ad 100644
--- a/test/passing/refs.janestreet/exp_grouping-parens.ml.ref
+++ b/test/passing/refs.janestreet/exp_grouping-parens.ml.ref
@@ -354,25 +354,9 @@ let _ = begin%ext end
 let _ = begin%ext end (* foo *)
 let _ = x y
 let _ = (* foo *) x y
-
-let _ =
-  begin%ext
-    x y
-  end
-;;
-
-let _ =
-  begin%ext
-    (* foo *) x y
-  end
-;;
-
-let _ =
-  begin[@landmark "parse_constant_dividends"]
-    market_data_items := ()
-  end
-;;
-
+let _ = begin%ext x y end
+let _ = begin%ext (* foo *) x y end
+let _ = begin[@landmark "parse_constant_dividends"] market_data_items := () end
 let () = if a then b (* asd *)
 
 let x =
@@ -635,12 +619,7 @@ let main =
   | B -> bbbbbbbbbbbbbbbbbbbbbb
 ;;
 
-let _ =
-  begin
-    a
-  end
-  [@a]
-;;
+let _ = begin a end [@a]
 
 let () =
   fooooo
diff --git a/test/passing/refs.janestreet/exp_grouping.ml.ref b/test/passing/refs.janestreet/exp_grouping.ml.ref
index b4f5dabfb5..718e739e33 100644
--- a/test/passing/refs.janestreet/exp_grouping.ml.ref
+++ b/test/passing/refs.janestreet/exp_grouping.ml.ref
@@ -391,36 +391,11 @@ let _ = begin end
 let _ = begin end (* foo *)
 let _ = begin%ext end
 let _ = begin%ext end (* foo *)
-
-let _ =
-  begin
-    x y
-  end
-;;
-
-let _ =
-  begin
-    (* foo *) x y
-  end
-;;
-
-let _ =
-  begin%ext
-    x y
-  end
-;;
-
-let _ =
-  begin%ext
-    (* foo *) x y
-  end
-;;
-
-let _ =
-  begin[@landmark "parse_constant_dividends"]
-    market_data_items := ()
-  end
-;;
+let _ = begin x y end
+let _ = begin (* foo *) x y end
+let _ = begin%ext x y end
+let _ = begin%ext (* foo *) x y end
+let _ = begin[@landmark "parse_constant_dividends"] market_data_items := () end
 
 let () =
   if a then begin
@@ -721,12 +696,7 @@ let main =
   | B -> bbbbbbbbbbbbbbbbbbbbbb
 ;;
 
-let _ =
-  begin
-    a
-  end
-  [@a]
-;;
+let _ = begin a end [@a]
 
 let () =
   fooooo
diff --git a/test/passing/refs.janestreet/extensions_exp_grouping.ml.ref b/test/passing/refs.janestreet/extensions_exp_grouping.ml.ref
index d873d1e429..35661c3516 100644
--- a/test/passing/refs.janestreet/extensions_exp_grouping.ml.ref
+++ b/test/passing/refs.janestreet/extensions_exp_grouping.ml.ref
@@ -1,46 +1,9 @@
-let _ =
-  begin%ext
-    y >>= z
-  end
-;;
-
-let _ =
-  [%ext
-    begin
-      y >>= z
-    end]
-;;
-
-let _ =
-  x
-  >>= begin%ext
-    y >>= z
-  end
-;;
-
-let _ =
-  x
-  >>= [%ext
-        begin
-          y >>= z
-        end]
-;;
-
-let _ =
-  f
-    begin%ext
-      y >>= z
-    end
-;;
-
-let _ =
-  f
-    [%ext
-      begin
-        y >>= z
-      end]
-;;
-
+let _ = begin%ext y >>= z end
+let _ = [%ext begin y >>= z end]
+let _ = x >>= begin%ext y >>= z end
+let _ = x >>= [%ext begin y >>= z end]
+let _ = f begin%ext y >>= z end
+let _ = f [%ext begin y >>= z end]
 let _ = (module%ext S)
 let _ = [%ext (module S)]
 let _ = f (module%ext S)
diff --git a/test/passing/refs.janestreet/source.ml.ref b/test/passing/refs.janestreet/source.ml.ref
index c624e3db2e..c77e626921 100644
--- a/test/passing/refs.janestreet/source.ml.ref
+++ b/test/passing/refs.janestreet/source.ml.ref
@@ -100,9 +100,7 @@ let () =
   assert%foo[@foo] true;
   lazy%foo[@foo] x;
   object%foo[@foo] end;
-  begin%foo[@foo]
-    3
-  end;
+  begin%foo[@foo] 3 end;
   new%foo[@foo] x;
   match%foo[@foo] () with
   | [%foo?
diff --git a/test/passing/refs.ocamlformat/attributes.ml.ref b/test/passing/refs.ocamlformat/attributes.ml.ref
index 7ed152a669..84125ff219 100644
--- a/test/passing/refs.ocamlformat/attributes.ml.ref
+++ b/test/passing/refs.ocamlformat/attributes.ml.ref
@@ -505,11 +505,7 @@ let _ =
 
 let _ = ((module[@a] X) [@b])
 
-let _ =
-  begin[@a]
-    x
-  end
-  [@b]
+let _ = begin[@a] x end [@b]
 
 let fold input ~init ~f =
   foldi input ~init ~f:(fun (_ : int) acc x -> f acc x) [@nontail]
diff --git a/test/passing/refs.ocamlformat/cases_exp_grouping.ml.ref b/test/passing/refs.ocamlformat/cases_exp_grouping.ml.ref
index ea51d7d0ea..a88ed14724 100644
--- a/test/passing/refs.ocamlformat/cases_exp_grouping.ml.ref
+++ b/test/passing/refs.ocamlformat/cases_exp_grouping.ml.ref
@@ -124,9 +124,7 @@ let a =
       bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
   end
 
-let a =
-  begin match f x i with A -> a | B -> b
-  end
+let a = begin match f x i with A -> a | B -> b end
 
 let a =
   begin[@a] match[@b]
@@ -201,9 +199,7 @@ let a =
       bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
   end
 
-let a =
-  begin try f x i with A -> a | B -> b
-  end
+let a = begin try f x i with A -> a | B -> b end
 
 let a =
   begin[@a] try[@b]
diff --git a/test/passing/refs.ocamlformat/exp_grouping-parens.ml.ref b/test/passing/refs.ocamlformat/exp_grouping-parens.ml.ref
index 8f10b4c4b1..4b6726b45f 100644
--- a/test/passing/refs.ocamlformat/exp_grouping-parens.ml.ref
+++ b/test/passing/refs.ocamlformat/exp_grouping-parens.ml.ref
@@ -300,20 +300,11 @@ let _ = x y
 
 let _ = (* foo *) x y
 
-let _ =
-  begin%ext
-    x y
-  end
+let _ = begin%ext x y end
 
-let _ =
-  begin%ext
-    (* foo *) x y
-  end
+let _ = begin%ext (* foo *) x y end
 
-let _ =
-  begin[@landmark "parse_constant_dividends"]
-    market_data_items := ()
-  end
+let _ = begin[@landmark "parse_constant_dividends"] market_data_items := () end
 
 let () = if a then b (* asd *)
 
@@ -552,11 +543,7 @@ let main =
   | B ->
       bbbbbbbbbbbbbbbbbbbbbb
 
-let _ =
-  begin
-    a
-  end
-  [@a]
+let _ = begin a end [@a]
 
 let () =
   fooooo
diff --git a/test/passing/refs.ocamlformat/exp_grouping.ml.ref b/test/passing/refs.ocamlformat/exp_grouping.ml.ref
index 65f27010e5..80e7b41157 100644
--- a/test/passing/refs.ocamlformat/exp_grouping.ml.ref
+++ b/test/passing/refs.ocamlformat/exp_grouping.ml.ref
@@ -333,30 +333,15 @@ let _ = begin%ext end
 
 let _ = begin%ext end (* foo *)
 
-let _ =
-  begin
-    x y
-  end
+let _ = begin x y end
 
-let _ =
-  begin
-    (* foo *) x y
-  end
+let _ = begin (* foo *) x y end
 
-let _ =
-  begin%ext
-    x y
-  end
+let _ = begin%ext x y end
 
-let _ =
-  begin%ext
-    (* foo *) x y
-  end
+let _ = begin%ext (* foo *) x y end
 
-let _ =
-  begin[@landmark "parse_constant_dividends"]
-    market_data_items := ()
-  end
+let _ = begin[@landmark "parse_constant_dividends"] market_data_items := () end
 
 let () =
   if a then begin
@@ -635,11 +620,7 @@ let main =
   | B ->
       bbbbbbbbbbbbbbbbbbbbbb
 
-let _ =
-  begin
-    a
-  end
-  [@a]
+let _ = begin a end [@a]
 
 let () =
   fooooo
diff --git a/test/passing/refs.ocamlformat/extensions-indent.ml.err b/test/passing/refs.ocamlformat/extensions-indent.ml.err
index cca4a42308..da4bd1e5cd 100644
--- a/test/passing/refs.ocamlformat/extensions-indent.ml.err
+++ b/test/passing/refs.ocamlformat/extensions-indent.ml.err
@@ -1 +1 @@
-Warning: extensions-indent.ml:503 exceeds the margin
+Warning: extensions-indent.ml:500 exceeds the margin
diff --git a/test/passing/refs.ocamlformat/extensions-indent.ml.ref b/test/passing/refs.ocamlformat/extensions-indent.ml.ref
index b134617a6a..13f6662c1a 100644
--- a/test/passing/refs.ocamlformat/extensions-indent.ml.ref
+++ b/test/passing/refs.ocamlformat/extensions-indent.ml.ref
@@ -181,10 +181,7 @@ let _ =
        let+ a = b in
        c]
 
-let _ =
-  begin%ext
-    "foo" ; "bar"
-  end
+let _ = begin%ext "foo" ; "bar" end
 
 let this_function_has_a_long_name plus very many arguments =
   "and a kind of long body"
diff --git a/test/passing/refs.ocamlformat/extensions.ml.err b/test/passing/refs.ocamlformat/extensions.ml.err
index d3952988ff..4142883aa4 100644
--- a/test/passing/refs.ocamlformat/extensions.ml.err
+++ b/test/passing/refs.ocamlformat/extensions.ml.err
@@ -1 +1 @@
-Warning: extensions.ml:503 exceeds the margin
+Warning: extensions.ml:500 exceeds the margin
diff --git a/test/passing/refs.ocamlformat/extensions.ml.ref b/test/passing/refs.ocamlformat/extensions.ml.ref
index 964f5d299b..8364979989 100644
--- a/test/passing/refs.ocamlformat/extensions.ml.ref
+++ b/test/passing/refs.ocamlformat/extensions.ml.ref
@@ -181,10 +181,7 @@ let _ =
     let+ a = b in
     c]
 
-let _ =
-  begin%ext
-    "foo" ; "bar"
-  end
+let _ = begin%ext "foo" ; "bar" end
 
 let this_function_has_a_long_name plus very many arguments =
   "and a kind of long body"
diff --git a/test/passing/refs.ocamlformat/extensions_exp_grouping.ml.ref b/test/passing/refs.ocamlformat/extensions_exp_grouping.ml.ref
index 5d3e96a15e..aa9020942b 100644
--- a/test/passing/refs.ocamlformat/extensions_exp_grouping.ml.ref
+++ b/test/passing/refs.ocamlformat/extensions_exp_grouping.ml.ref
@@ -1,39 +1,14 @@
-let _ =
-  begin%ext
-    y >>= z
-  end
+let _ = begin%ext y >>= z end
 
-let _ =
-  [%ext
-    begin
-      y >>= z
-    end]
+let _ = [%ext begin y >>= z end]
 
-let _ =
-  x
-  >>= begin%ext
-    y >>= z
-  end
+let _ = x >>= begin%ext y >>= z end
 
-let _ =
-  x
-  >>= [%ext
-        begin
-          y >>= z
-        end]
+let _ = x >>= [%ext begin y >>= z end]
 
-let _ =
-  f
-    begin%ext
-      y >>= z
-    end
+let _ = f begin%ext y >>= z end
 
-let _ =
-  f
-    [%ext
-      begin
-        y >>= z
-      end]
+let _ = f [%ext begin y >>= z end]
 
 let _ = (module%ext S)
 
diff --git a/test/passing/refs.ocamlformat/js_begin.ml.ref b/test/passing/refs.ocamlformat/js_begin.ml.ref
index 87e266fd96..f35f826e29 100644
--- a/test/passing/refs.ocamlformat/js_begin.ml.ref
+++ b/test/passing/refs.ocamlformat/js_begin.ml.ref
@@ -2,6 +2,4 @@ let f = function zoo -> begin foo ; bar end
 
 let g = function zoo -> foo ; bar
 
-let () =
-  begin match foo with Bar -> snoo
-  end
+let () = begin match foo with Bar -> snoo end
diff --git a/test/passing/refs.ocamlformat/js_pattern.ml.ref b/test/passing/refs.ocamlformat/js_pattern.ml.ref
index b126b25d05..1fb99f971e 100644
--- a/test/passing/refs.ocamlformat/js_pattern.ml.ref
+++ b/test/passing/refs.ocamlformat/js_pattern.ml.ref
@@ -6,9 +6,7 @@ let f = function _ -> 0
 
 let f x = match x with _ -> 0
 
-let f x =
-  begin match x with _ -> 0
-  end
+let f x = begin match x with _ -> 0 end
 
 let check_price t = function
   | {Exec.trade_at_settlement= None | Some false} ->
diff --git a/test/passing/refs.ocamlformat/reformat_string.ml.ref b/test/passing/refs.ocamlformat/reformat_string.ml.ref
index c2dfa0fb5c..5988c193d5 100644
--- a/test/passing/refs.ocamlformat/reformat_string.ml.ref
+++ b/test/passing/refs.ocamlformat/reformat_string.ml.ref
@@ -6,15 +6,9 @@ let _ = (* test *) "asd"
 
 let _ = "asd"
 
-let _ =
-  begin
-    (* te""st *) "asd"
-  end
-
-let _ =
-  begin
-    "asd"
-  end
+let _ = begin (* te""st *) "asd" end
+
+let _ = begin "asd" end
 
 let _ = 'a'
 
diff --git a/test/passing/refs.ocamlformat/source.ml.err b/test/passing/refs.ocamlformat/source.ml.err
index 37900d4c2d..c0c2125caa 100644
--- a/test/passing/refs.ocamlformat/source.ml.err
+++ b/test/passing/refs.ocamlformat/source.ml.err
@@ -1,3 +1,3 @@
-Warning: source.ml:6495 exceeds the margin
-Warning: source.ml:7369 exceeds the margin
-Warning: source.ml:7887 exceeds the margin
+Warning: source.ml:6493 exceeds the margin
+Warning: source.ml:7367 exceeds the margin
+Warning: source.ml:7885 exceeds the margin
diff --git a/test/passing/refs.ocamlformat/source.ml.ref b/test/passing/refs.ocamlformat/source.ml.ref
index 9333078ed7..3dacef7d26 100644
--- a/test/passing/refs.ocamlformat/source.ml.ref
+++ b/test/passing/refs.ocamlformat/source.ml.ref
@@ -107,9 +107,7 @@ let () =
   assert%foo[@foo] true ;
   lazy%foo[@foo] x ;
   object%foo[@foo] end ;
-  begin%foo[@foo]
-    3
-  end ;
+  begin%foo[@foo] 3 end ;
   new%foo[@foo] x ;
   match%foo[@foo] () with
   | [%foo?
diff --git a/test/unit/test_fmt_ast.ml b/test/unit/test_fmt_ast.ml
index 071a5e7c5c..56c33c67fb 100644
--- a/test/unit/test_fmt_ast.ml
+++ b/test/unit/test_fmt_ast.ml
@@ -114,7 +114,7 @@ let updated_ast_tests =
         check_updated_test "[%extension 1]" "[%extension 1]" ;
         check_updated_test "function _ -> ." "function _ -> ." ;
         check_updated_test "_" "_" ;
-        check_updated_test "begin () end" "begin\n  ()\nend" ;
+        check_updated_test "begin () end" "begin () end" ;
         check_updated_test "a :: b" "a :: b" ;
         check_updated_test "a.!(b)" "a.!(b)" ;
         check_updated_test "a.!(b) <- c" "a.!(b) <- c" ;