--- /dev/null
+++ b/calendar.opam
@@ -0,0 +1,25 @@
+opam-version: "2.0"
+version: "dev"
+author: "Julien Signoles"
+maintainer: "ocaml-community"
+license: "LGPL-2.1 with OCaml linking exception"
+synopsis: "Library for handling dates and times in your program"
+build: [
+  ["dune" "build" "-p" name]
+  ["dune" "build" "@doc" "-p" name] {with-doc}
+  ["dune" "runtest" "-p" name] {with-test}
+]
+depends: [
+  "re"
+  "dune" {build}
+  "odoc" {with-doc}
+  "alcotest" {with-test}
+]
+tags: [ "calendar" "date" "time" "datetime" ]
+homepage: "https://github.com/ocaml-community/calendar"
+doc: "https://ocaml-community.github.io/calendar/"
+bug-reports: "https://github.com/ocaml-community/calendar/issues"
+dev-repo: "git+https://github.com/ocaml-community/calendar"
+description:"""
+Calendar is a library for handling dates and times in your program.
+"""
--- /dev/null
+++ b/dune-project
@@ -0,0 +1 @@
+(lang dune 1.0)
--- a/src/date.ml
+++ b/src/date.ml
@@ -70,7 +70,7 @@ let hash = Utils.Int.hash
 (* Constructors. *)
 
 let lt (d1 : int * int * int) (d2 : int * int * int) =
-  Pervasives.compare d1 d2 < 0
+  Stdlib.compare d1 d2 < 0
 
 (* [date_ok] returns [true] is the date belongs to the Julian period;
    [false] otherwise. *)
@@ -249,10 +249,10 @@ module Period = struct
   let sub x y = { m = x.m - y.m; d = x.d - y.d }
   let opp x = { m = - x.m; d = - x.d }
 
-  (* exactly equivalent to [Pervasives.compare] but more flexible typing *)
+  (* exactly equivalent to [Stdlib.compare] but more flexible typing *)
   let compare x y =
-    let n = Pervasives.compare x.m y.m in
-    if n = 0 then Pervasives.compare x.d y.d else n
+    let n = Stdlib.compare x.m y.m in
+    if n = 0 then Stdlib.compare x.d y.d else n
   let equal x y = compare x y = 0
   let hash = Hashtbl.hash
 
@@ -337,7 +337,7 @@ let weeks_in_year y =
     | _   -> 52
 
 let week_first_last w y =
-  let d = make y 1 1 in
+  let d = make y 1 4 in (* January 4th must be in the first week (ISO 8601) *)
   let d = d - d mod 7 in
   let b = d + 7 * (w - 1) in
   b, 6 + b
--- /dev/null
+++ b/src/dune
@@ -0,0 +1,16 @@
+(library
+  (name calendarLib)
+  (public_name calendar)
+  (libraries re unix)
+  (modules_without_implementation calendar_sig date_sig period time_sig)
+  (flags :standard -warn-error -32 -safe-string))
+
+(rule
+  (targets version.ml)
+  (action
+    (with-stdout-to %{targets}
+      (progn
+        (echo "let version = String.trim \"" %{version:calendar} "\"\n")
+        (echo "let date = String.trim \"")
+        (echo "\"\n")))))
+
--- a/src/printer.ml
+++ b/src/printer.ml
@@ -121,7 +121,7 @@ let gen_day_of_name f fmt name =
 let day_of_name = gen_day_of_name name_of_day "%a"
 let day_of_short_name = gen_day_of_name short_name_of_day "%A"
 
-let word_regexp = ref (Str.regexp "[a-zA-Z]+")
+let word_regexp = ref (Re.Str.regexp "[a-zA-Z]+")
 
 let set_word_regexp r = word_regexp := r
 
@@ -181,7 +181,7 @@ struct
     let print_int pad k n = print_number fmt pad k (Lazy.force n) in
     let print_string pad s =
       let pad s = match pad with
-	| Uppercase -> String.uppercase s
+	| Uppercase -> String.uppercase_ascii s
 	| Empty | Zero | Blank -> s
       in
       Format.pp_print_string fmt (pad (Lazy.force s))
@@ -236,7 +236,7 @@ struct
 	| 'n' -> print_char '\n'
 	| 'p' -> print_string pad apm
 	| 'P' ->
-	    Format.pp_print_string fmt (String.lowercase (Lazy.force apm))
+	    Format.pp_print_string fmt (String.lowercase_ascii (Lazy.force apm))
 	| 'r' ->
 	    print_time pad shour;
 	    print_char ' ';
@@ -259,10 +259,10 @@ struct
 	    print_number fmt Zero 10 0
 	| ':' ->
 	    let idx =
-	      try Str.search_forward (Str.regexp "z\\|:z\\|::z") f (i+1)
+	      try Re.Str.search_forward (Re.Str.regexp "z\\|:z\\|::z") f (i+1)
 	      with Not_found -> bad_format f
 	    in
-	    let next = Str.matched_string f in
+	    let next = Re.Str.matched_string f in
 	    if idx <> i+1 then bad_format f;
 	    if Lazy.force tz >= 0 then print_char '+';
 	    print_int pad 10 tz;
@@ -352,15 +352,15 @@ struct
     in
     let read_word ?(regexp=(!word_regexp)) () =
       let jn =
-	try Str.search_forward regexp s !j with Not_found -> not_match f s
+	try Re.Str.search_forward regexp s !j with Not_found -> not_match f s
       in
       if jn <> !j then not_match f s;
-      let w = Str.matched_string s in
+      let w = Re.Str.matched_string s in
       j := jn + String.length w;
       w
     in
     let read_float =
-      let regexp = Str.regexp "[0-9][0-9]\\(\\.[0-9]*\\)?" in
+      let regexp = Re.Str.regexp "[0-9][0-9]\\(\\.[0-9]*\\)?" in
       fun () ->
         try float_of_string (read_word ~regexp ())
         with Failure _ -> not_match f s
@@ -390,7 +390,7 @@ struct
     let parse_y () = year := read_number 2 + 1900 in
     let parse_Y () = year := read_number 4 in
     let parse_tz () =
-      let sign = match read_word ~regexp:(Str.regexp "[\\+-]") () with
+      let sign = match read_word ~regexp:(Re.Str.regexp "[\\+-]") () with
 	| "+" -> -1
 	| "-" -> 1
 	| _ -> assert false
--- a/src/printer.mli
+++ b/src/printer.mli
@@ -125,7 +125,7 @@ val short_name_of_month : Date.month ->
     [name_of_month d].
     Used by the specifier [%b]. *)
 
-val set_word_regexp: Str.regexp -> unit
+val set_word_regexp: Re.Str.regexp -> unit
   (** Set the regular expression used to recognize words in
       [from_fstring]. Default is [[a-zA-Z]*].
       @since 1.10 *)
--- a/src/time_Zone.ml
+++ b/src/time_Zone.ml
@@ -44,7 +44,6 @@ let gap_gmt_local =
 let current () = !tz
 
 let change = function
-  | UTC_Plus x when out_of_bounds x -> invalid_arg "Not a valid time zone"
   | _ as t -> tz := t
 
 let gap t1 t2 =
--- a/src/utils.ml
+++ b/src/utils.ml
@@ -29,8 +29,8 @@ end
 
 module Int = struct
   type t = int
-  let equal = Pervasives.(=)
-  let compare = Pervasives.compare
+  let equal = Stdlib.(=)
+  let compare = Stdlib.compare
   let hash = Hashtbl.hash
 end
 
@@ -38,7 +38,7 @@ module Float = struct
 
   type t = float
 
-  let precision = ref 1e-3
+  let precision = ref 1e-8
 
   let set_precision f = precision := f
 
--- a/src/utils.mli
+++ b/src/utils.mli
@@ -58,8 +58,8 @@ module Float: sig
   val set_precision: float -> unit
     (** Set the precision of [equal] and [compare] for float.
 	If the precision is [p], then the floats [x] and [y] are equal iff
-	[abs(x-y) < p].  By default, the precision is [1e-3] (that is one
-	millisecond if floats represents seconds). *)
+	[abs(x-y) < p].  By default, the precision is [1e-8] (that is 0.864
+	milliseconds if floats represent days). *)
 
   val round: t -> int
     (** Round a float to the nearest integer. *)
--- /dev/null
+++ b/tests/dune
@@ -0,0 +1,8 @@
+(executable
+  (name test)
+  (libraries calendar))
+
+(alias
+  (name runtest)
+  (deps  test.exe)
+  (action (run ./test.exe -e)))
--- a/tests/test_timezone.ml
+++ b/tests/test_timezone.ml
@@ -29,6 +29,7 @@ open Time_Zone;;
 include Gen_test;;
 reset ();;
 
+change UTC;;
 test (current () = UTC) "current () = UTC";;
 change Local;;
 test (current () = Local) "current () = Local";;