diff --git a/CHANGES.md b/CHANGES.md
index 21c06e98ba1..5e711e75822 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -91,24 +91,27 @@
 - Get rid of ad-hoc rules for guessing the version. Dune now only
   relies on the version written in the `dune-project` file and no
   longer read `VERSION` or similar files (#2541, @diml)
-  
-- In `(diff? x y)` action, require `x` to exist and register a 
+
+- In `(diff? x y)` action, require `x` to exist and register a
   dependency on that file. (#2486, @aalekseyev)
 
 - On Windows, an .exe suffix is no longer added implicitly to binary names that
   already end in .exe. Second, when resolving binary names, .opt variants are no
   longer chosen automatically. (#2543, @nojb)
 
-- Make `(diff? x y)` move the correction file (`y`) away from the build 
-  directory to promotion staging area.
-  This makes corrections work with sandboxing and in general reduces build 
-  directory pollution. (#2486, @aalekseyev, fixes #2482)
+- Make `(diff? x y)` move the correction file (`y`) away from the build
+  directory to promotion staging area. This makes corrections work with
+  sandboxing and in general reduces build directory pollution. (#2486,
+  @aalekseyev, fixes #2482)
 
 - Fix a ppx hash collision in watch mode (#2546, fixes #2520, @diml)
 
 - Remove the optimisation of passing `-nodynlink` for executalbes when
   not necessary. It seems to be breaking things (see #2527, @diml)
 
+- Fix invalid library names in `dune-package` files. Only public names should
+  exist in such files. (#2558, fix #2425, @rgrinberg)
+
 1.11.0 (23/07/2019)
 -------------------
 
diff --git a/src/dune/install_rules.ml b/src/dune/install_rules.ml
index fa88c34065e..09ccad300ca 100644
--- a/src/dune/install_rules.ml
+++ b/src/dune/install_rules.ml
@@ -268,7 +268,7 @@ let gen_dune_package sctx pkg =
           let libs =
             Super_context.libs_of_package sctx pkg.name
             |> Lib.Local.Set.to_list
-            |> List.map ~f:(fun lib ->
+            |> Result.List.map ~f:(fun lib ->
               let dir_contents =
                 let info = Lib.Local.info lib in
                 let dir = Lib_info.src_dir info in
@@ -289,6 +289,7 @@ let gen_dune_package sctx pkg =
               Lib.to_dune_lib lib
                 ~dir:(Path.build (lib_root lib))
                 ~modules ~foreign_objects)
+            |> Result.ok_exn
           in
           Dune_package.Or_meta.Dune_package
             { Dune_package.version = pkg.version
diff --git a/src/dune/lib.ml b/src/dune/lib.ml
index 9efccf4dc08..9812a4fa9d0 100644
--- a/src/dune/lib.ml
+++ b/src/dune/lib.ml
@@ -148,9 +148,9 @@ module Error = struct
     let name = Lib_info.name private_dep in
     make ~loc
       [ Pp.textf
-        "Library %S is private, it cannot be a dependency of a public library."
-          (Lib_name.to_string name)
-      ; Pp.textf "You need to give %S a public name." (Lib_name.to_string name)
+        "Library %S is private, it cannot be a dependency of a public \
+         library. You need to give %S a public name."
+        (Lib_name.to_string name) (Lib_name.to_string name)
       ]
 
   let not_virtual_lib ~loc ~impl ~not_vlib =
@@ -1755,15 +1755,34 @@ let to_dune_lib ({ name; info; _ } as lib) ~modules ~foreign_objects ~dir =
   let synopsis = Lib_info.synopsis info in
   let archives = Lib_info.archives info in
   let plugins = Lib_info.plugins info in
-  let implements = Lib_info.implements info in
   let modes = Lib_info.modes info in
   let kind = Lib_info.kind info in
   let version = Lib_info.version info in
   let jsoo_runtime = Lib_info.jsoo_runtime info in
   let special_builtin_support = Lib_info.special_builtin_support info in
-  let default_implementation = Lib_info.default_implementation info in
   let known_implementations = Lib_info.known_implementations info in
   let foreign_archives = Lib_info.foreign_archives info in
+  let use_public_name ~lib_field ~info_field =
+    match (info_field, lib_field) with
+    | Some _, None
+     |None, Some _ ->
+      assert false
+    | None, None -> Ok None
+    | Some (loc, _), Some field ->
+      let open Result.O in
+      let+ field = field in
+      Some (loc, field.name)
+  in
+  let open Result.O in
+  let* implements =
+    use_public_name ~info_field:(Lib_info.implements info)
+      ~lib_field:(implements lib)
+  in
+  let+ default_implementation =
+    use_public_name
+      ~info_field:(Lib_info.default_implementation info)
+      ~lib_field:(Option.map ~f:Lazy.force lib.default_implementation)
+  in
   Dune_package.Lib.make ~obj_dir ~orig_src_dir ~name ~loc ~kind ~synopsis
     ~version ~archives ~plugins ~foreign_archives ~foreign_objects
     ~jsoo_runtime
diff --git a/src/dune/lib.mli b/src/dune/lib.mli
index 1cff767b1b3..46947c6c4e5 100644
--- a/src/dune/lib.mli
+++ b/src/dune/lib.mli
@@ -269,7 +269,7 @@ val to_dune_lib :
   -> modules:Modules.t
   -> foreign_objects:Path.t list
   -> dir:Path.t
-  -> (Syntax.Version.t * Dune_lang.t list) Dune_package.Lib.t
+  -> (Syntax.Version.t * Dune_lang.t list) Dune_package.Lib.t Or_exn.t
 
 module Local : sig
   type lib
diff --git a/test/blackbox-tests/test-cases/private-public-overlap/run.t b/test/blackbox-tests/test-cases/private-public-overlap/run.t
index e09babe7025..912cdd64305 100644
--- a/test/blackbox-tests/test-cases/private-public-overlap/run.t
+++ b/test/blackbox-tests/test-cases/private-public-overlap/run.t
@@ -6,8 +6,7 @@ public libraries may not have private dependencies
   8 |  (libraries privatelib)
                   ^^^^^^^^^^
   Error: Library "privatelib" is private, it cannot be a dependency of a public
-  library.
-  You need to give "privatelib" a public name.
+  library. You need to give "privatelib" a public name.
       ocamldep .publiclib.objs/publiclib.ml.d
   [1]
 
@@ -33,8 +32,7 @@ Unless they introduce private runtime dependencies:
   16 |   (pps private_ppx))
               ^^^^^^^^^^^
   Error: Library "private_runtime_dep" is private, it cannot be a dependency of
-  a public library.
-  You need to give "private_runtime_dep" a public name.
+  a public library. You need to give "private_runtime_dep" a public name.
         ocamlc .private_ppx.objs/byte/private_ppx.{cmi,cmo,cmt}
       ocamlopt .private_ppx.objs/native/private_ppx.{cmx,o}
       ocamlopt private_ppx.{a,cmxa}
diff --git a/test/blackbox-tests/test-cases/vlib-default-impl/dune-package/a-default/dune b/test/blackbox-tests/test-cases/vlib-default-impl/dune-package/a-default/dune
new file mode 100644
index 00000000000..40724106b6b
--- /dev/null
+++ b/test/blackbox-tests/test-cases/vlib-default-impl/dune-package/a-default/dune
@@ -0,0 +1,4 @@
+(library
+ (name a_default)
+ (public_name a.default-impl)
+ (implements a))
diff --git a/test/blackbox-tests/test-cases/vlib-default-impl/dune-package/a-default/x.ml b/test/blackbox-tests/test-cases/vlib-default-impl/dune-package/a-default/x.ml
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/test/blackbox-tests/test-cases/vlib-default-impl/dune-package/dune b/test/blackbox-tests/test-cases/vlib-default-impl/dune-package/dune
index 7296346d618..0c357acc58a 100644
--- a/test/blackbox-tests/test-cases/vlib-default-impl/dune-package/dune
+++ b/test/blackbox-tests/test-cases/vlib-default-impl/dune-package/dune
@@ -1,7 +1,7 @@
 (library
  (public_name a)
  (virtual_modules x)
- (default_implementation a-default))
+ (default_implementation a_default))
 
 (rule
  (with-stdout-to
diff --git a/test/blackbox-tests/test-cases/vlib-default-impl/run.t b/test/blackbox-tests/test-cases/vlib-default-impl/run.t
index 7698b48f40d..d1236fb899a 100644
--- a/test/blackbox-tests/test-cases/vlib-default-impl/run.t
+++ b/test/blackbox-tests/test-cases/vlib-default-impl/run.t
@@ -41,7 +41,7 @@ Check that default implementation data is installed in the dune package file.
    (kind normal)
    (virtual)
    (foreign_archives (native a$ext_lib))
-   (default_implementation a-default)
+   (default_implementation a.default-impl)
    (main_module_name A)
    (modes byte native)
    (modules
@@ -56,6 +56,32 @@ Check that default implementation data is installed in the dune package file.
       (kind alias)
       (impl))
      (wrapped true))))
+  (library
+   (name a.default-impl)
+   (kind normal)
+   (archives
+    (byte default-impl/a_default.cma)
+    (native default-impl/a_default.cmxa))
+   (plugins
+    (byte default-impl/a_default.cma)
+    (native default-impl/a_default.cmxs))
+   (foreign_archives (native default-impl/a_default$ext_lib))
+   (requires a)
+   (implements a)
+   (main_module_name A)
+   (modes byte native)
+   (modules
+    (wrapped
+     (main_module_name A)
+     (modules
+      ((name X) (obj_name a__X) (visibility public) (kind impl_vmodule) (impl)))
+     (alias_module
+      (name A__a_default__)
+      (obj_name a__a_default__)
+      (visibility public)
+      (kind alias)
+      (impl))
+     (wrapped true))))
 
 Test default implementation for an external library
 
diff --git a/test/blackbox-tests/test-cases/vlib/run.t b/test/blackbox-tests/test-cases/vlib/run.t
index 917493fa5ee..1fc20eba3b3 100644
--- a/test/blackbox-tests/test-cases/vlib/run.t
+++ b/test/blackbox-tests/test-cases/vlib/run.t
@@ -328,7 +328,7 @@ Include variants and implementation information in dune-package
    (plugins (byte impl/impl.cma) (native impl/impl.cmxs))
    (foreign_archives (native impl/impl$ext_lib))
    (requires foo.vlib)
-   (implements vlib)
+   (implements foo.vlib)
    (main_module_name Vlib)
    (modes byte native)
    (modules