diff --git a/dune-project b/dune-project
index 0decfd1b8..cc0ccfc3e 100644
--- a/dune-project
+++ b/dune-project
@@ -18,8 +18,8 @@
 "\| open Tyxml;
 "\| let to_reason = <a href=\"reasonml.github.io/\"> \"Reason!\" </a>
 "\| ```
-"\|  
-"\| The TyXML JSX allow to write TyXML documents with reason's JSX syntax. 
+"\|
+"\| The TyXML JSX allow to write TyXML documents with reason's JSX syntax.
 "\| It works with textual trees, virtual DOM trees, or any TyXML module.
 )
  (depends
@@ -35,13 +35,13 @@
 (package
  (name tyxml-ppx)
  (synopsis "PPX to write TyXML documents with the HTML syntax")
- (description 
+ (description
 "\| ```ocaml
 "\| open Tyxml
 "\| let%html to_ocaml = \"<a href='ocaml.org'>OCaml!</a>\"
 "\| ```
-"\|  
-"\| The TyXML PPX allow to write TyXML documents using the traditional HTML syntax. 
+"\|
+"\| The TyXML PPX allow to write TyXML documents using the traditional HTML syntax.
 "\| It works with textual trees, virtual DOM trees, or any TyXML module.
 )
  (depends
@@ -53,7 +53,9 @@
   (markup
    (>= 0.7.2))
   (ppxlib
-   (>= 0.18))))
+   (>= 0.18))
+  (re
+   (>= 1.5.0))))
 
 (package
  (name tyxml-syntax)
diff --git a/tyxml-jsx.opam b/tyxml-jsx.opam
index 05babce7d..f634341d0 100644
--- a/tyxml-jsx.opam
+++ b/tyxml-jsx.opam
@@ -6,8 +6,8 @@ description: """
 open Tyxml;
 let to_reason = <a href="reasonml.github.io/"> "Reason!" </a>
 ```
- 
-The TyXML JSX allow to write TyXML documents with reason's JSX syntax. 
+
+The TyXML JSX allow to write TyXML documents with reason's JSX syntax.
 It works with textual trees, virtual DOM trees, or any TyXML module.
 """
 maintainer: ["dev@ocsigen.org"]
diff --git a/tyxml-ppx.opam b/tyxml-ppx.opam
index 3b97f528a..1ef8e2ec0 100644
--- a/tyxml-ppx.opam
+++ b/tyxml-ppx.opam
@@ -6,8 +6,8 @@ description: """
 open Tyxml
 let%html to_ocaml = "<a href='ocaml.org'>OCaml!</a>"
 ```
- 
-The TyXML PPX allow to write TyXML documents using the traditional HTML syntax. 
+
+The TyXML PPX allow to write TyXML documents using the traditional HTML syntax.
 It works with textual trees, virtual DOM trees, or any TyXML module.
 """
 maintainer: ["dev@ocsigen.org"]
@@ -24,6 +24,7 @@ depends: [
   "alcotest" {with-test}
   "markup" {>= "0.7.2"}
   "ppxlib" {>= "0.18"}
+  "re" {>= "1.5.0"}
   "odoc" {with-doc}
 ]
 build: [
diff --git a/tyxml-syntax.opam b/tyxml-syntax.opam
index 5c04ead8b..2a5064fc4 100644
--- a/tyxml-syntax.opam
+++ b/tyxml-syntax.opam
@@ -9,7 +9,7 @@ doc: "https://ocsigen.org/tyxml/latest/manual/intro"
 bug-reports: "https://github.com/ocsigen/tyxml/issues"
 depends: [
   "dune" {>= "2.7"}
-  "ocaml" {>= "4.04"}
+  "ocaml" {>= "4.03"}
   "alcotest" {with-test}
   "ppxlib" {>= "0.18"}
   "re" {>= "1.5.0"}
diff --git a/tyxml.opam b/tyxml.opam
index d6384fd8f..3f9b2e251 100644
--- a/tyxml.opam
+++ b/tyxml.opam
@@ -11,7 +11,7 @@ doc: "https://ocsigen.org/tyxml/latest/manual/intro"
 bug-reports: "https://github.com/ocsigen/tyxml/issues"
 depends: [
   "dune" {>= "2.7"}
-  "ocaml" {>= "4.04"}
+  "ocaml" {>= "4.03"}
   "alcotest" {with-test}
   "re" {>= "1.5.0"}
   "seq"