diff --git a/src/stages/5-ast_typed/PP_json.ml b/src/stages/5-ast_typed/PP_json.ml
index 745483ebc..d700c65b3 100644
--- a/src/stages/5-ast_typed/PP_json.ml
+++ b/src/stages/5-ast_typed/PP_json.ml
@@ -76,13 +76,23 @@ module M = struct
         `Assoc ["typeVariableMap",  `List lst'] );
     }
 
-  let print : ((no_state, json) fold_config -> no_state -> 'a -> json) -> 'a -> json = fun fold v ->
+  let to_json : ((no_state, json) fold_config -> no_state -> 'a -> json) -> 'a -> json = fun fold v ->
     fold to_json NoState v
+  
+  let print : ((no_state, json) fold_config -> no_state -> 'a -> json) -> formatter -> 'a -> unit  = fun fold ppf v ->
+    fprintf ppf "%a" Yojson.Basic.pp (to_json fold v)
 end
 
+module Yojson = Fold.Folds(struct
+  type in_state = M.no_state ;;
+  type out_state = json ;;
+  type 'a t = 'a -> json ;;
+  let f = M.to_json ;;
+end)
+
 include Fold.Folds(struct
   type in_state = M.no_state ;;
   type out_state = json ;;
-  type 'a t = 'a -> json ;;
+  type 'a t = formatter -> 'a -> unit ;;
   let f = M.print ;;
 end)
diff --git a/src/stages/5-ast_typed/formatter.ml b/src/stages/5-ast_typed/formatter.ml
index f6c331722..e42269786 100644
--- a/src/stages/5-ast_typed/formatter.ml
+++ b/src/stages/5-ast_typed/formatter.ml
@@ -4,7 +4,7 @@ let program_ppformat ~display_format f (typed,_) =
   match display_format with
   | Human_readable | Dev -> PP.program f typed
 
-let program_jsonformat (typed,_) : json = PP_json.program typed
+let program_jsonformat (typed,_) : json = PP_json.Yojson.program typed
 
 let program_format : 'a format = {
   pp = program_ppformat;