diff --git a/gitlab-pages/docs/advanced/entrypoints-contracts.md b/gitlab-pages/docs/advanced/entrypoints-contracts.md
index 7b8e901b4..0aef5b6bf 100644
--- a/gitlab-pages/docs/advanced/entrypoints-contracts.md
+++ b/gitlab-pages/docs/advanced/entrypoints-contracts.md
@@ -95,7 +95,7 @@ type action is
 | Reset of unit
 ```
 
-```pascaligo gorup=d
+```pascaligo skip
 // proxy.ligo
 #include "counter.types.ligo"
 
diff --git a/src/passes/1-parser/cameligo.ml b/src/passes/1-parser/cameligo.ml
index 859f4ccd1..53ecdc29e 100644
--- a/src/passes/1-parser/cameligo.ml
+++ b/src/passes/1-parser/cameligo.ml
@@ -33,15 +33,22 @@ module Errors = struct
               file
     in
     let message () = str in
-    let loc = Region.make 
-      ~start:(Pos.from_byte start) 
-      ~stop:(Pos.from_byte end_) 
+    let loc = if start.pos_cnum = -1 then
+      Region.make
+        ~start: Pos.min
+        ~stop:(Pos.from_byte end_)    
+    else
+      Region.make
+        ~start:(Pos.from_byte start)
+        ~stop:(Pos.from_byte end_)
+    in 
+    let data =
+      [
+        ("parser_loc",
+          fun () -> Format.asprintf "%a" Location.pp_lift @@ loc
+        )
+      ]    
     in
-    let data = [
-      ("parser_loc", 
-        fun () -> Format.asprintf "%a" Location.pp_lift @@ loc
-      )      
-    ] in
     error ~data title message
   
   let unrecognized_error source (start: Lexing.position) (end_: Lexing.position) lexbuf = 
diff --git a/src/passes/1-parser/pascaligo.ml b/src/passes/1-parser/pascaligo.ml
index 5431c00a5..2cf59bb3b 100644
--- a/src/passes/1-parser/pascaligo.ml
+++ b/src/passes/1-parser/pascaligo.ml
@@ -70,16 +70,23 @@ module Errors = struct
               end_.pos_lnum (end_.pos_cnum - end_.pos_bol)
               file
     in
-    let message () = str in
-    let loc = Region.make
-      ~start:(Pos.from_byte start)
-      ~stop:(Pos.from_byte end_)
+    let message () = str in    
+    let loc = if start.pos_cnum = -1 then
+      Region.make
+        ~start: Pos.min
+        ~stop:(Pos.from_byte end_)    
+    else
+      Region.make
+        ~start:(Pos.from_byte start)
+        ~stop:(Pos.from_byte end_)
+    in 
+    let data =
+      [
+        ("parser_loc",
+          fun () -> Format.asprintf "%a" Location.pp_lift @@ loc
+        )
+      ]    
     in
-    let data = [
-      ("parser_loc",
-        fun () -> Format.asprintf "%a" Location.pp_lift @@ loc
-      )
-    ] in
     error ~data title message
 
   let unrecognized_error source (start: Lexing.position) (end_: Lexing.position) lexbuf =
diff --git a/src/passes/1-parser/reasonligo.ml b/src/passes/1-parser/reasonligo.ml
index 7bb7ab0cf..c919ef399 100644
--- a/src/passes/1-parser/reasonligo.ml
+++ b/src/passes/1-parser/reasonligo.ml
@@ -44,15 +44,22 @@ module Errors = struct
               file
     in
     let message () = str in
-    let loc = Region.make
-      ~start:(Pos.from_byte start)
-      ~stop:(Pos.from_byte end_)
+    let loc = if start.pos_cnum = -1 then
+      Region.make
+        ~start: Pos.min
+        ~stop:(Pos.from_byte end_)    
+    else
+      Region.make
+        ~start:(Pos.from_byte start)
+        ~stop:(Pos.from_byte end_)
+    in 
+    let data =
+      [
+        ("parser_loc",
+          fun () -> Format.asprintf "%a" Location.pp_lift @@ loc
+        )
+      ]    
     in
-    let data = [
-      ("location",
-        fun () -> Format.asprintf "%a" Location.pp_lift @@ loc
-      )
-    ] in
     error ~data title message
 
   let unrecognized_error source (start: Lexing.position) (end_: Lexing.position) lexbuf =
diff --git a/src/test/md_file_tests.ml b/src/test/md_file_tests.ml
index eb89fa4a5..6d8d491de 100644
--- a/src/test/md_file_tests.ml
+++ b/src/test/md_file_tests.ml
@@ -8,6 +8,11 @@ let failed_to_compile_md_file md_file (s,group,prg) =
   let content () = "\n"^prg in
   error title content
 
+let bad_code_block_argument arg =
+  let title () = Format.asprintf "Bad code block argument '%s'" arg in
+  let content () = "only 'group=NAME' or 'skip' are allowed" in
+  error title content
+
 (**
   binds the snippets by (syntax, group_name)
   e.g. :(pascaligo, a) -> "let .. in let .. in"
@@ -19,34 +24,39 @@ let get_groups md_file =
   let channel = open_in md_file in
   let lexbuf = Lexing.from_channel channel in
   let code_blocks = Md.token lexbuf in
-  List.fold_left
+  bind_fold_list
     (fun (grp_map: _ SnippetsGroup.t) (el:Md.block) ->
       match el.header  with
-      | Some s when (String.equal s "pascaligo") || (String.equal s "cameligo") || (String.equal s "reasonligo") -> (
+      | Some ("pascaligo" as s) | Some ("cameligo" as s) | Some ("reasonligo" as s) -> (
+        let%bind () = bind_iter_list
+          (fun arg -> match arg with
+          | Md.Field "" | Md.Field "skip" | Md.NameValue ("group",_) -> ok ()
+          | Md.Field f | Md.NameValue (f,_) -> fail @@ bad_code_block_argument f)
+          el.arguments in
         match el.arguments with
-        | [Md.Field ""] -> SnippetsGroup.update (s,"ungrouped")
+        | [Md.Field ""] ->
+          ok @@ SnippetsGroup.update (s,"ungrouped")
                   (fun arg_content ->
                     match arg_content with
                     | Some ct -> Some (String.concat "\n" (ct::el.contents))
                     | None -> Some (String.concat "\n" el.contents)
                   )
                   grp_map
-        | [Md.Field "skip"] -> grp_map
-        | _ ->
-        List.fold_left
+        | [Md.Field "skip"] -> ok grp_map
+        | _ -> bind_fold_list
           (fun grp_map arg -> match arg with
               | Md.NameValue ("group", name) ->
-                SnippetsGroup.update (s,name)
+                ok @@ SnippetsGroup.update (s,name)
                   (fun arg_content ->
                     match arg_content with
                     | Some ct -> Some (String.concat "\n" (ct::el.contents))
                     | None -> Some (String.concat "\n" el.contents)
                   )
                   grp_map
-              | _ -> grp_map
+              | _ -> ok grp_map
           )
           grp_map el.arguments )
-      | None | Some _ -> grp_map
+      | None | Some _ -> ok grp_map
     )
     SnippetsGroup.empty code_blocks
 
@@ -69,8 +79,9 @@ let compile_groups _filename grp_list =
   ok ()
 
 let compile filename () =
-  let groups = SnippetsGroup.bindings @@ get_groups filename in
-  let%bind () = compile_groups filename groups in
+  let%bind groups = get_groups filename in
+  let groups_map = SnippetsGroup.bindings groups in
+  let%bind () = compile_groups filename groups_map in
   ok ()
 
 (*