diff --git a/src/alias.ml b/src/alias.ml
index fe5182c1..c391aedd 100644
--- a/src/alias.ml
+++ b/src/alias.ml
@@ -3,12 +3,14 @@ open! Import
 (** Fully qualified name *)
 module Fq_name : sig
   type t
+  val pp : Format.formatter -> t -> unit
   val make : Path.t -> t
   val path : t -> Path.t
 end = struct
   type t = Path.t
   let make t = t
   let path t = t
+  let pp = Path.pp
 end
 
 type t =
@@ -16,6 +18,10 @@ type t =
   ; file : Path.t
   }
 
+let pp fmt t =
+  Format.fprintf fmt "@[<2>{ name@ =@ %a@ ;@ file@ =@ %a }@]"
+    Path.pp (Fq_name.path t.name) Path.pp t.file
+
 let aliases_path = Path.(relative root) "_build/.aliases"
 
 let suffix = "-" ^ String.make 32 '0'
@@ -113,8 +119,24 @@ module Store = struct
     { alias : t
     ; mutable deps : Path.Set.t
     }
+  let pp_entry fmt entry =
+    let pp_deps fmt deps =
+      Format.pp_print_list Path.pp fmt (Path.Set.elements deps) in
+    Format.fprintf fmt "@[<2>{@ alias@ =@ %a@ ;@ deps@ = (%a)@ }@]"
+      pp entry.alias pp_deps entry.deps
+
   type t = (Fq_name.t, entry) Hashtbl.t
 
+  let pp fmt (t : t) =
+    let bindings = Hashtbl.fold ~init:[] ~f:(fun ~key ~data acc ->
+      (key, data)::acc
+    ) t in
+    let pp_bindings fmt b =
+      Format.pp_print_list (fun fmt (k, v) ->
+        Format.fprintf fmt "@[<2>(%a@ %a)@]" Fq_name.pp k pp_entry v
+      ) fmt b in
+    Format.fprintf fmt "Store.t@ @[@<2>(%a)@]" pp_bindings bindings
+
   let create () = Hashtbl.create 1024
 end
 
diff --git a/src/alias.mli b/src/alias.mli
index 0bcae570..502432df 100644
--- a/src/alias.mli
+++ b/src/alias.mli
@@ -1,5 +1,9 @@
+open Import
+
 type t
 
+val pp : t Fmt.t
+
 val make : string -> dir:Path.t -> t
 
 val of_path : Path.t -> t
@@ -51,6 +55,9 @@ val name_of_file : Path.t -> string option
 
 module Store : sig
   type t
+
+  val pp : t Fmt.t
+
   val create : unit -> t
 end
 
diff --git a/src/import.ml b/src/import.ml
index 279ec789..4c3f84b9 100644
--- a/src/import.ml
+++ b/src/import.ml
@@ -504,3 +504,7 @@ let open_out_gen = `Use_Io
 module No_io = struct
   module Io = struct end
 end
+
+module Fmt = struct
+  type 'a t = Format.formatter -> 'a -> unit
+end
diff --git a/src/path.ml b/src/path.ml
index 9aefa25b..996fd267 100644
--- a/src/path.ml
+++ b/src/path.ml
@@ -424,3 +424,5 @@ let rm_rf =
 let change_extension ~ext t =
   let t = try Filename.chop_extension t with Not_found -> t in
   t ^ ext
+
+let pp = Format.pp_print_string
diff --git a/src/path.mli b/src/path.mli
index 1fc5f699..31d781d2 100644
--- a/src/path.mli
+++ b/src/path.mli
@@ -111,3 +111,5 @@ val rm_rf : t -> unit
 
 (** Changes the extension of the filename (or adds an extension if there was none) *)
 val change_extension : ext:string -> t -> t
+
+val pp : t Fmt.t