diff --git a/src/plugins/dive/build.mli b/src/plugins/dive/build.mli
index b4be1c5807da72cd4325b1cbe1841ce99925aa96..0f494984a6d0997f35daef712b920bc30a39017a 100644
--- a/src/plugins/dive/build.mli
+++ b/src/plugins/dive/build.mli
@@ -38,4 +38,4 @@ val explore_backward : depth:int -> t -> node -> unit
 val show : t -> node -> unit
 val hide : t -> node -> unit
 
-val reduce_to_horizon : t -> int option range -> node -> unit
+val reduce_to_horizon : t -> range -> node -> unit
diff --git a/src/plugins/dive/dive_types.ml b/src/plugins/dive/dive_types.ml
index 732043390e4b3e3887231f1d07fedee2fe02e986..057cb6ff6bd11213e0ac951dc846ee0f789c5c8a 100644
--- a/src/plugins/dive/dive_types.ml
+++ b/src/plugins/dive/dive_types.ml
@@ -76,12 +76,12 @@ type graph_diff = {
   removed_nodes: node list;
 }
 
-type 'a range = {
-  backward: 'a;
-  forward: 'a;
+type range = {
+  backward: int option;
+  forward: int option;
 }
 
 type window = {
-  perception: int option range; (* depth of exploration *)
-  horizon: int option range; (* hide beyond horizon ; None for infinite *)
+  perception: range; (* depth of exploration *)
+  horizon: range; (* hide beyond horizon ; None for infinite *)
 }
diff --git a/src/plugins/dive/server_interface.ml b/src/plugins/dive/server_interface.ml
index dc881ea4522292dcecf78611cfa4bf366d1c3bf1..f7280c57840dde2100fbc4298245445f8021b873 100644
--- a/src/plugins/dive/server_interface.ml
+++ b/src/plugins/dive/server_interface.ml
@@ -69,7 +69,7 @@ let origin_to_locations = function
       callsites
 
 
-module Range : Data.S with type t = int option range =
+module Range : Data.S with type t = range =
 struct
   include Record ()
 
@@ -80,7 +80,7 @@ struct
 
   let descr = "Parametrization of the exploration range."
   include (val publish "range" ~descr)
-  type t = int option range
+  type t = range
 
   let to_json r=
     default |>