diff --git a/CHANGES.md b/CHANGES.md
index 88775b03..0694e67d 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -9,6 +9,8 @@ unreleased
 - Remove reduntant module type copy from migrate_504_503, preventing
   exponential blowup with many "with" constraints. (#644, @smuenzel)
 
+- Fix the 5.4/5.3 migration of attributes on package types (#650, @dra27)
+
 0.38.0
 ------
 
diff --git a/astlib/encoding_504.ml b/astlib/encoding_504.ml
index 771e524f..028632a5 100644
--- a/astlib/encoding_504.ml
+++ b/astlib/encoding_504.ml
@@ -10,6 +10,11 @@ module Ext_name = struct
   let bivariant_pmty_with = "ppxlib.migration.bivariant_pmty_with_5_4"
 end
 
+module Attr_name = struct
+  (* An attribute name used for splitting package type attributes. *)
+  let split_package_attributes = "ppxlib.migration.split_package_attributes_5_4"
+end
+
 let invalid_encoding ~loc name = Error.invalid_encoding ~loc ~version:"5.4" name
 
 module type AST = sig
diff --git a/astlib/encoding_504.mli b/astlib/encoding_504.mli
index a6ec797b..220a4dcb 100644
--- a/astlib/encoding_504.mli
+++ b/astlib/encoding_504.mli
@@ -7,6 +7,10 @@ module Ext_name : sig
   val bivariant_pmty_with : string
 end
 
+module Attr_name : sig
+  val split_package_attributes : string
+end
+
 module To_503 : sig
   open Ast_503.Asttypes
   open Ast_503.Parsetree
diff --git a/astlib/migrate_503_504.ml b/astlib/migrate_503_504.ml
index b492b148..cc057a0d 100644
--- a/astlib/migrate_503_504.ml
+++ b/astlib/migrate_503_504.ml
@@ -406,12 +406,43 @@ and copy_core_type : Ast_503.Parsetree.core_type -> Ast_504.Parsetree.core_type
        Ast_503.Parsetree.ptyp_loc_stack;
        Ast_503.Parsetree.ptyp_attributes;
      } ->
-  {
-    Ast_504.Parsetree.ptyp_desc = copy_core_type_desc ptyp_desc;
-    Ast_504.Parsetree.ptyp_loc = copy_location ptyp_loc;
-    Ast_504.Parsetree.ptyp_loc_stack = copy_location_stack ptyp_loc_stack;
-    Ast_504.Parsetree.ptyp_attributes = copy_attributes ptyp_attributes;
-  }
+  match ptyp_desc with
+  | Ptyp_package (name, constraints) ->
+      let rec split_attributes (typ, pkg) = function
+        | [] -> (List.rev typ, List.rev pkg)
+        | attr :: attrs
+          when String.equal attr.Ast_503.Parsetree.attr_name.txt
+                 Encoding_504.Attr_name.split_package_attributes ->
+            (List.rev typ, attrs)
+        | attr :: attrs -> split_attributes (attr :: typ, pkg) attrs
+      in
+      let typ_attrs, pkg_attrs = split_attributes ([], []) ptyp_attributes in
+      let pkg : Ast_504.Parsetree.package_type =
+        {
+          ppt_path = copy_loc (copy_Longident_t ~loc:name.loc) name;
+          ppt_cstrs =
+            List.map
+              (fun (a, b) ->
+                ( copy_loc (copy_Longident_t ~loc:a.Ast_503.Asttypes.loc) a,
+                  copy_core_type b ))
+              constraints;
+          ppt_loc = ptyp_loc;
+          ppt_attrs = copy_attributes pkg_attrs;
+        }
+      in
+      {
+        Ast_504.Parsetree.ptyp_desc = Ast_504.Parsetree.Ptyp_package pkg;
+        Ast_504.Parsetree.ptyp_loc = copy_location ptyp_loc;
+        Ast_504.Parsetree.ptyp_loc_stack = copy_location_stack ptyp_loc_stack;
+        Ast_504.Parsetree.ptyp_attributes = copy_attributes typ_attrs;
+      }
+  | _ ->
+      {
+        Ast_504.Parsetree.ptyp_desc = copy_core_type_desc ptyp_desc;
+        Ast_504.Parsetree.ptyp_loc = copy_location ptyp_loc;
+        Ast_504.Parsetree.ptyp_loc_stack = copy_location_stack ptyp_loc_stack;
+        Ast_504.Parsetree.ptyp_attributes = copy_attributes ptyp_attributes;
+      }
 
 and copy_location_stack :
     Ast_503.Parsetree.location_stack -> Ast_504.Parsetree.location_stack =
diff --git a/astlib/migrate_504_503.ml b/astlib/migrate_504_503.ml
index 0767d96e..63f17b58 100644
--- a/astlib/migrate_504_503.ml
+++ b/astlib/migrate_504_503.ml
@@ -12,6 +12,17 @@ end
 let bivariant_error ~loc =
   Error.migration_error ~loc ~from:"5.4" ~to_:"5.3" "bivariant type parameters"
 
+let split_package_attr =
+  let attr_name =
+    Ast_503.Asttypes.
+      {
+        txt = Encoding_504.Attr_name.split_package_attributes;
+        loc = Location.none;
+      }
+  in
+  Ast_503.Parsetree.
+    { attr_name; attr_loc = Location.none; attr_payload = PStr [] }
+
 let rec copy_toplevel_phrase :
     Ast_504.Parsetree.toplevel_phrase -> Ast_503.Parsetree.toplevel_phrase =
   function
@@ -194,7 +205,8 @@ and copy_expression_desc ~loc :
           ptyp_desc = package;
           ptyp_loc = Location.none;
           ptyp_loc_stack = [];
-          ptyp_attributes = [];
+          ptyp_attributes =
+            split_package_attr :: copy_attributes c.Ast_504.Parsetree.ppt_attrs;
         }
       in
       Ast_503.Parsetree.Pexp_constraint (exp, ct)
@@ -403,11 +415,18 @@ and copy_core_type : Ast_504.Parsetree.core_type -> Ast_503.Parsetree.core_type
        Ast_504.Parsetree.ptyp_attributes;
      } ->
   let loc = copy_location ptyp_loc in
+  let package_attrs =
+    match ptyp_desc with
+    | Ast_504.Parsetree.Ptyp_package { Ast_504.Parsetree.ppt_attrs; _ } ->
+        split_package_attr :: copy_attributes ppt_attrs
+    | _ -> []
+  in
   {
     Ast_503.Parsetree.ptyp_desc = copy_core_type_desc ~loc ptyp_desc;
     Ast_503.Parsetree.ptyp_loc = loc;
     Ast_503.Parsetree.ptyp_loc_stack = copy_location_stack ptyp_loc_stack;
-    Ast_503.Parsetree.ptyp_attributes = copy_attributes ptyp_attributes;
+    Ast_503.Parsetree.ptyp_attributes =
+      copy_attributes ptyp_attributes @ package_attrs;
   }
 
 and copy_location_stack :
diff --git a/test/504_migrations/package-types/dune b/test/504_migrations/package-types/dune
new file mode 100644
index 00000000..7d5145e8
--- /dev/null
+++ b/test/504_migrations/package-types/dune
@@ -0,0 +1,13 @@
+(executable
+ (name id_driver)
+ (modules id_driver)
+ (libraries ppxlib))
+
+(cram
+ ; Somewhat confusingly we enable this test on 5.5 and above, even
+ ; though it is a test for 5.4 migrations. We need this Pprintast bug
+ ; fix (https://github.com/ocaml/ocaml/pull/14797) which did not make
+ ; it back to 5.4, to really test this.
+ (enabled_if
+  (>= %{ocaml_version} "5.5"))
+ (deps id_driver.exe))
diff --git a/test/504_migrations/package-types/id_driver.ml b/test/504_migrations/package-types/id_driver.ml
new file mode 100644
index 00000000..e3cba404
--- /dev/null
+++ b/test/504_migrations/package-types/id_driver.ml
@@ -0,0 +1 @@
+let () = Ppxlib.Driver.standalone ()
diff --git a/test/504_migrations/package-types/run.t b/test/504_migrations/package-types/run.t
new file mode 100644
index 00000000..40181e47
--- /dev/null
+++ b/test/504_migrations/package-types/run.t
@@ -0,0 +1,30 @@
+The signature for package types, as well as packed expressions changed
+in between.
+
+Originally we had a bug in the migrations that would silently drop some
+attributes. Now we split them internally and when migrating back to compiler's
+that can distinguish these attributes we make sure to split them back
+correctly.
+
+  $ cat > test.ml << EOF
+  > module type S = sig type t end
+  > let f (module K : S with type t = int [@foo]) = ()
+  > let f (module K : S with type t = (int [@foo])) = ()
+  > let f (module K : S with type t = (int [@foo])[@bar]) = ()
+  > type t = (module S [@inner])[@outer]
+  > 
+  > EOF
+
+  $ ./id_driver.exe test.ml
+  module type S  = sig type t end
+  let f ((module K)  : (((module S with type t = int))[@foo ])) = ()
+  let f ((module K)  : (module S with type t = ((int)[@foo ]))) = ()
+  let f ((module K)  : (((module S with type t = ((int)[@foo ])))[@bar ])) = ()
+  type t = (((module S))[@outer ][@inner ])
+  $ ./id_driver.exe --use-compiler-pp test.ml
+  module type S  = sig type t end
+  let f (module K : ((S with type t = int)[@foo ])) = ()
+  let f (module K : S with type t = ((int)[@foo ])) = ()
+  let f (module K : ((S with type t = ((int)[@foo ]))[@bar ])) = ()
+  type t = (((module ((S)[@inner ])))[@outer ])
+