diff --git a/bin/main.ml b/bin/main.ml
index ddb6973..2273e02 100644
--- a/bin/main.ml
+++ b/bin/main.ml
@@ -18,7 +18,7 @@ let generate_atd state input_format paths =
     | Input_format.JSONSchema -> Generator.make_atd_of_jsonschema ~state
     | OpenAPI -> Generator.make_atd_of_openapi ~state
   in
-  print_endline (Generator.base (String.concat " " (List.map Filename.basename paths)));
+  print_endline (Generator.base state (String.concat " " (List.map Filename.basename paths)));
   let root =
     match paths with
     | [ _ ] -> `Default
@@ -46,13 +46,14 @@ let main =
   let doc = "Generate an ATD file from a list of JSON Schema / OpenAPI document" in
   let state_term =
     Term.(
-      const (fun skip_doc pad toplevel_types avoid_dangling_refs ->
+      const (fun skip_doc pad toplevel_types avoid_dangling_refs json_ocaml_type ->
         Generator.
           {
             with_doc = not skip_doc;
             protect_against_duplicates = (if pad then Some (ref []) else None);
             toplevel_types;
             avoid_dangling_refs;
+            json_ocaml_type;
           }
       )
       $ Arg.(value (flag (info [ "skip-doc" ] ~doc:"Skip documentation annotations.")))
@@ -66,6 +67,12 @@ let main =
           )
         )
       $ Arg.(value (flag (info [ "avoid-dangling-refs" ] ~doc:"Convert dangling refs to json.")))
+      $ Arg.(
+          value
+            (opt (pair ~sep:':' string string) Generator.default_state.json_ocaml_type
+               (info [ "json-ocaml-type" ] ~docv:"MODULE.PATH:TYPE-NAME" ~doc:"Use an alternate Mod.type for `json`.")
+            )
+        )
     )
   in
   let paths = Arg.(non_empty & pos_all file [] & info [] ~docv:"FILES" ~doc) in
diff --git a/lib/generator.ml b/lib/generator.ml
index 03f9b4f..7b596a3 100644
--- a/lib/generator.ml
+++ b/lib/generator.ml
@@ -7,10 +7,17 @@ type state = {
   protect_against_duplicates : string list ref option;
   toplevel_types : [ `All | `Only of string list ];
   avoid_dangling_refs : bool;
+  json_ocaml_type : string * string;
 }
 
 let default_state =
-  { with_doc = true; protect_against_duplicates = None; toplevel_types = `All; avoid_dangling_refs = false }
+  {
+    with_doc = true;
+    protect_against_duplicates = None;
+    toplevel_types = `All;
+    avoid_dangling_refs = false;
+    json_ocaml_type = "Yojson.Basic", "t";
+  }
 
 let record_field_name _state str =
   let cleaned_field_name = Utils.sanitize_name str in
@@ -289,13 +296,14 @@ let process_schemas state (schemas : (string * schema or_ref) list) =
     )
     [] schemas
 
-let base from =
+let base state from =
+  let module_path, type_t = state.json_ocaml_type in
   sprintf
     {|(* Generated by jsonschema2atd from %s *)
-type json <ocaml module="Yojson.Basic" t="t"> = abstract
+type json <ocaml module="%s" t="%s"> = abstract
 type int64 = int <ocaml repr="int64">
 |}
-    from
+    from module_path type_t
 
 let make_atd_of_schemas state schemas =
   let schemas =