diff --git a/src/lsp/cobol_indent/indent_check.ml b/src/lsp/cobol_indent/indent_check.ml
index f93788a5b..4fabf7048 100644
--- a/src/lsp/cobol_indent/indent_check.ml
+++ b/src/lsp/cobol_indent/indent_check.ml
@@ -48,6 +48,7 @@ open Indent_util
 type text = Cobol_preproc.Text.t
 
 let rec check_ident_div (text:text) (state:indent_state) (ifcheck:bool) =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -118,6 +119,7 @@ let rec check_ident_div (text:text) (state:indent_state) (ifcheck:bool) =
 (*************ENVIRONMENT DIVISION****************)
 (*TODO:Add check of clause in ENV DIVISION if need be*)
 and check_env_div (text:text)  (state:indent_state) (ifcheck:bool)  =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -184,6 +186,7 @@ and check_env_div (text:text)  (state:indent_state) (ifcheck:bool)  =
 (*************DATA DIVISION****************)
 (*TODO: Refine the check of clause of DATA DIVISION*)
 and check_data_div (text:text) (state:indent_state) ifcheck  =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -264,6 +267,7 @@ and check_data_div (text:text) (state:indent_state) ifcheck  =
         check_data_div wordlist {state with context; acc} false
 
 and check_data_div_entry clauses key (text:text) state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -319,6 +323,7 @@ and check_data_desc text state ifcheck =
 
 (*************PROCEDURE DIVISION****************)
 and check_proc_div_header (text:text) (state:indent_state) ifcheck =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -360,6 +365,7 @@ and check_proc_div_header (text:text) (state:indent_state) ifcheck =
       check_proc_div_header wordlist {state with context; acc} false
 
 and check_proc_div (text:text) (state:indent_state) ifcheck   =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | {payload = TextWord "IDENTIFICATION"; _} :: {payload = TextWord "DIVISION"; _}
@@ -477,6 +483,7 @@ and check_proc_div (text:text) (state:indent_state) ifcheck   =
    	    call `check_statement`.
 *)
 and check_statement (text:text) state ifcheck  =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -627,6 +634,7 @@ and check_statement (text:text) state ifcheck  =
   however, there are too many duplicate code to write...
   we could do that if the finer analysis is needed.  *)
 and check_if_stmt (text:text) state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -660,6 +668,7 @@ and check_if_stmt (text:text) state ifcheck =
              when check the wordlist, check the `context` top, if there is a DUMMY token,
              call `check_statement`                                                            *)
 and check_raise_stmt (text:text) state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -675,6 +684,7 @@ and check_raise_stmt (text:text) state ifcheck =
         check_statement text state ifcheck
 
 and check_goback_stmt (text:text) state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -709,6 +719,7 @@ and check_goback_stmt (text:text) state ifcheck =
         check_statement text state ifcheck
 
 and check_use_stmt (text:text) state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -731,6 +742,7 @@ and check_use_stmt (text:text) state ifcheck =
 (*For alignment of arguments*)
 (*fst_arg: if is the first argument in the line*)
 and check_arguments (text:text) state ifcheck ~fst_arg =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
@@ -798,6 +810,7 @@ and check_divide_stmt text state ifcheck = check_add_stmt text state ifcheck
    the check_function will call itself again (possibly stay in its scope) (except `check_statement`)
    the handle_function handles one token and go directly to another scope *)
 and handle_open_scope keyword loc wordlist state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context = imp_scope_termination state.context in
   let offset = offset_of_context context in
   let acc = check_pos loc offset state.acc ifcheck in
@@ -812,6 +825,7 @@ and handle_open_scope keyword loc wordlist state ifcheck =
       check_fun keyword wordlist {state with scope = keyword; context; acc} false
 
 and handle_close_scope keyword loc wordlist state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context = exp_scope_termination keyword state.context in
   match context with
   | (key, _) :: ((prev, offset) :: _ as context) when key = keyword ->
@@ -828,6 +842,7 @@ and handle_close_scope keyword loc wordlist state ifcheck =
   | _ ->  failwith @@ failure_msg loc
 
 and handle_if_then loc wordlist state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context = imp_scope_termination state.context in
   match context with
   | (THEN, _):: (IF, _) :: context' ->
@@ -837,6 +852,7 @@ and handle_if_then loc wordlist state ifcheck =
       failwith @@ failure_msg loc
 
 and handle_else loc wordlist state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context = exp_scope_termination THEN state.context in
   match context with
   | (THEN, _) :: ((IF, _) :: context' as context) ->
@@ -848,6 +864,7 @@ and handle_else loc wordlist state ifcheck =
 
 (*for alignment of argument*)
 and handle_operator keyword loc wordlist state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context = phrase_termination state.context in
   let offset = offset_of_context context in
   let acc = check_pos loc offset state.acc ifcheck in
@@ -868,6 +885,7 @@ and handle_giving loc wordlist state ifcheck =
   handle_operator GIVING loc wordlist state ifcheck
 
 and handle_by loc wordlist state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context = phrase_termination_until USING state.context in
   let offset = offset_of_context context in
   let acc = check_pos loc offset state.acc ifcheck in
@@ -878,6 +896,7 @@ and handle_by loc wordlist state ifcheck =
 (*using-phrase is the only phrase that we treat more carefully
   using-phrase can contain by content/reference phrase.       *)
 and handle_using loc text state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context = phrase_termination state.context in
   let offset = offset_of_context context in
   let acc = check_pos loc offset state.acc ifcheck in
@@ -905,6 +924,7 @@ and check_using (text:text) state ifcheck =
 
 
 and handle_phrase keyword loc wordlist state ifcheck =
+  let check_pos = check_pos state.src_format in
   match keyword with
   | TO -> handle_to loc wordlist state ifcheck
   | INTO -> handle_into loc wordlist state ifcheck
@@ -925,6 +945,7 @@ and handle_phrase keyword loc wordlist state ifcheck =
       | _ -> failwith @@ failure_msg loc
 
 and handle_inline_phrase loc wordlist state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context = phrase_termination state.context in
   let offset = offset_of_context context in
   let acc = check_pos loc offset state.acc ifcheck in
@@ -935,6 +956,7 @@ and handle_inline_phrase loc wordlist state ifcheck =
 
 
 and handle_conditional_statement loc keyword wordlist state ifcheck =
+  let check_pos = check_pos state.src_format in
   let help keyword rev_keyword keyword_associated =
     let context, acc = state.context, state.acc in
     let context = phrase_termination context in
@@ -990,6 +1012,7 @@ and handle_conditional_statement loc keyword wordlist state ifcheck =
 
 
 and handle_when loc wordlist state ifcheck =
+  let check_pos = check_pos state.src_format in
   let context = phrase_termination state.context in
   match context with
   | (key, offset) :: _ when key = EVALUATE || key = SEARCH ->
@@ -1017,6 +1040,7 @@ and handle_when loc wordlist state ifcheck =
 
 
 and end_compilation_unit loc wordlist ({context; acc; _} as state) ifcheck =
+  let check_pos = check_pos state.src_format in
   let context = exp_scope_termination COMPILATION_UNIT context in
   let context =
     match context with
@@ -1030,6 +1054,7 @@ and end_compilation_unit loc wordlist ({context; acc; _} as state) ifcheck =
 (*Remark: if the COPY does not copy a complete paragraph/statement/data entry...,
           but a phrase/clause/identifier..., the check_copy_replace does not work *)
 and check_copy_replace (text:text) (state:indent_state) (ifcheck:bool)  =
+  let check_pos = check_pos state.src_format in
   let context, acc = state.context, state.acc in
   match text with
   | [] -> state
diff --git a/src/lsp/cobol_indent/indent_type.ml b/src/lsp/cobol_indent/indent_type.ml
index 87d22439b..37fd9bf7d 100644
--- a/src/lsp/cobol_indent/indent_type.ml
+++ b/src/lsp/cobol_indent/indent_type.ml
@@ -145,7 +145,13 @@ ex.
 type indent_record =
   { lnum:int;
     offset_orig:int;
-    offset_modif: int}
+    offset_modif: int;
+    src_format: Cobol_preproc.Src_format.any
+      (** This is the source format for the change. Ideally, this information
+      should not have to be recorded here, but could be obtained from the line
+      number -- however, we don't have the infrastructure for that currently.
+      *)
+  }
 
 type range = {start_line:int;
               end_line  :int  }
diff --git a/src/lsp/cobol_indent/indent_util.ml b/src/lsp/cobol_indent/indent_util.ml
index 45530e552..8e042ef42 100644
--- a/src/lsp/cobol_indent/indent_util.ml
+++ b/src/lsp/cobol_indent/indent_util.ml
@@ -16,7 +16,13 @@ open Cobol_common.Srcloc
 open Indent_type
 open Indent_keywords
 
-let check_pos (pos:Lexing.position) (offset:int) (ind_recds:indent_record list) ~print_errors=
+let check_pos
+  (src_format : Cobol_preproc.Src_format.any)
+  (pos:Lexing.position)
+  (offset:int)
+  (ind_recds:indent_record list)
+  ~print_errors
+=
   let real_offset = pos.pos_cnum - pos.pos_bol in
   if real_offset <> offset then
     begin
@@ -28,7 +34,8 @@ let check_pos (pos:Lexing.position) (offset:int) (ind_recds:indent_record list)
       end;
     {lnum = pos.pos_lnum;
      offset_orig = real_offset;
-     offset_modif = offset }
+     offset_modif = offset;
+     src_format }
     :: ind_recds
     end
   else
@@ -37,12 +44,12 @@ let check_pos (pos:Lexing.position) (offset:int) (ind_recds:indent_record list)
 (* print_errors for debug *)
 let check_pos = check_pos ~print_errors:false
 
-let check_pos srcloc offset ind_recds ifcheck =
-  if ifcheck
-  then
+let check_pos src_format srcloc offset ind_recds ifcheck =
+  match src_format with
+  | Cobol_preproc.Src_format.SF (NoIndic, FreePaging) when ifcheck ->
     let pos = start_pos srcloc in
-    check_pos pos offset ind_recds
-  else ind_recds
+    check_pos src_format pos offset ind_recds
+  | _ -> ind_recds
 
 let failure_msg loc =
   let pos = start_pos loc in
diff --git a/src/lsp/cobol_indent/indent_util.mli b/src/lsp/cobol_indent/indent_util.mli
index b61e59c22..4cce27ee4 100644
--- a/src/lsp/cobol_indent/indent_util.mli
+++ b/src/lsp/cobol_indent/indent_util.mli
@@ -13,7 +13,13 @@
 
 open Indent_type
 
-val check_pos: Cobol_common.Srcloc.srcloc -> int -> indent_record list -> bool -> indent_record list
+val check_pos:
+  Cobol_preproc.Src_format.any ->
+  Cobol_common.Srcloc.srcloc ->
+  int ->
+  indent_record list ->
+  bool ->
+  indent_record list
 
 val failure_msg: Cobol_common.Srcloc.srcloc -> string
 
diff --git a/src/lsp/cobol_indent/indenter.ml b/src/lsp/cobol_indent/indenter.ml
index 2d00f8005..42019de98 100644
--- a/src/lsp/cobol_indent/indenter.ml
+++ b/src/lsp/cobol_indent/indenter.ml
@@ -20,13 +20,13 @@ open Indent_type
   range: range of file to indent
   result: the Cobol code correctly indented (string)
 *)
-let indenter ~source_format (str:string) (rdl:indent_record list) range =
-  let do_one_record (strl:string list) (rd:indent_record) =
+let indenter (str:string) (rdl:indent_record list) range =
+  let do_one_record (strl:string array) (rd:indent_record) =
     let lnum = rd.lnum in
     let offset = rd.offset_modif - rd.offset_orig in
-    let str = List.nth strl (lnum - 1) in
+    let str = strl.(lnum - 1) in
     let newstr =
-      match source_format with
+      match rd.src_format with
       | Cobol_preproc.Src_format.SF (NoIndic, FreePaging) ->
         if offset > 0 then
           let space = String.make offset ' ' in
@@ -59,10 +59,11 @@ let indenter ~source_format (str:string) (rdl:indent_record list) range =
       | SF (TrmIndic, FixedWidth _) -> str
       | SF (CBLXIndic, FixedWidth _) -> str
     in
-    List.mapi (fun i str -> if i = lnum - 1 then newstr else str) (strl)
+    strl.(lnum - 1) <- newstr
   in
-  let strl = String.split_on_char '\n' str in
-  let strl = List.fold_left (fun acc rd -> do_one_record acc rd) strl rdl in
+  let strl = String.split_on_char '\n' str |> Array.of_list in
+  List.iter (fun rd -> do_one_record strl rd) rdl;
+  let strl = Array.to_list strl in
   let strl =
     match range with
     | None -> strl
@@ -73,10 +74,12 @@ let indenter ~source_format (str:string) (rdl:indent_record list) range =
 
 (*indent a range of file, with the default indent_config*)
 let indent_range ~dialect ~source_format ~range ~filename ~contents =
-  (* Note: this value doesn't actually matter, it will be overriden
-      immediately by [fold_source_lines] calling [on_initial_source_format]
-      below. *)
-  let src_format = Cobol_preproc.Src_format.from_config SFFixed in
+  let src_format =
+    (* Note: this value doesn't actually matter, it will be overriden
+       immediately by [fold_source_lines] calling [on_initial_source_format]
+       below. *)
+    Cobol_preproc.Src_format.from_config SFFixed
+  in
   let state =
     Cobol_preproc.fold_source_lines ~dialect ~source_format
       ~on_initial_source_format:(fun src_format st -> { st with src_format })
@@ -91,9 +94,7 @@ let indent_range ~dialect ~source_format ~range ~filename ~contents =
       { src_format; scope = BEGIN; context  = []; acc = []; range }
   in
   (* NB: note here we ignore diagnostics *)
-  let ind_recds = state.result.acc in
-  indenter
-    ~source_format:state.result.src_format contents ind_recds state.result.range
+  indenter contents state.result.acc state.result.range
 
 (*indent a range of file, with the user-defined indent_config*)
 let indent_range ~dialect ~source_format ~indent_config ~range ~filename ~contents =
@@ -101,4 +102,4 @@ let indent_range ~dialect ~source_format ~indent_config ~range ~filename ~conten
     | Some indent_config -> Indent_config.set_config ~indent_config
     | None -> ()
   end;
-  indent_range ~dialect ~source_format ~range ~filename ~contents
\ No newline at end of file
+  indent_range ~dialect ~source_format ~range ~filename ~contents