diff --git a/src/core/model_parser.ml b/src/core/model_parser.ml
index 6a0673f9cce6f96296b392279493fb3d58813814..1ab8c0624d71fceb07c57e88138f3e1f144d4798 100644
--- a/src/core/model_parser.ml
+++ b/src/core/model_parser.ml
@@ -283,7 +283,7 @@ let print_model_elements_on_lines_json me_name_to_str fmt model_file =
 let print_model_json
     ?(me_name_trans = why_name_trans)
     fmt
-    ~model =
+    model =
   let me_name_to_str = fun me ->
     me_name_trans (me.me_name, me.me_type) in
   Json.map_bindings
@@ -295,7 +295,7 @@ let print_model_json
 let model_to_string_json
     ?(me_name_trans = why_name_trans)
     model =
-  print_model_json str_formatter ~me_name_trans ~model;
+  print_model_json str_formatter ~me_name_trans model;
   flush_str_formatter ()
 
 
diff --git a/src/core/model_parser.mli b/src/core/model_parser.mli
index 06b82133bf8e070fe382df15c9b2996719c7cf60..93a5785d0bf34e16250626a1988478f1f3995d09 100644
--- a/src/core/model_parser.mli
+++ b/src/core/model_parser.mli
@@ -132,7 +132,7 @@ val model_to_string :
 val print_model_json :
   ?me_name_trans:((string * model_element_type) -> string) ->
   Format.formatter ->
-  model:model ->
+  model ->
   unit
 (** Prints counter-example model to json format.