diff --git a/src/dune/findlib/findlib.ml b/src/dune/findlib/findlib.ml
index 6848e0b3cbc..318820feb4c 100644
--- a/src/dune/findlib/findlib.ml
+++ b/src/dune/findlib/findlib.ml
@@ -184,7 +184,7 @@ module Loader : sig
   val lookup_and_load :
     db -> Package.Name.t -> (Dune_package.t, Unavailable_reason.t) result
 
-  val dummy_package : db -> Package.Name.t -> Dune_package.t
+  val dummy_package : db -> Lib_name.t -> Dune_package.t
 end = struct
   module Findlib_package : sig
     type t =
@@ -439,12 +439,22 @@ end = struct
       ~meta_file:(Path.of_string "<internal>")
       ~meta
 
-  let dummy_package db name =
-    load_builtin db
-      { name = Some (Lib_name.of_package_name name)
-      ; vars = String.Map.empty
-      ; subs = []
-      }
+  let dummy_package db lib_name =
+    let pkg, names = Lib_name.split lib_name in
+    let top_lib = Lib_name.of_package_name pkg in
+    let dummy name subs =
+      { Meta.Simplified.name = Some name; vars = String.Map.empty; subs }
+    in
+    let subs : Meta.Simplified.t list =
+      let rec loop = function
+        | [] -> []
+        | name :: names ->
+          [ dummy (Lib_name.of_string_exn ~loc:None name) (loop names) ]
+      in
+      loop names
+    in
+    let meta = dummy top_lib subs in
+    load_builtin db meta
 
   let lookup_and_load_one_dir db ~dir ~name =
     let meta_file = Path.relative dir meta_fn in
@@ -493,8 +503,8 @@ end
 
 type t = db
 
-let dummy_package t ~name =
-  let p = Loader.dummy_package t (Lib_name.package_name name) in
+let dummy_lib t ~name =
+  let p = Loader.dummy_package t name in
   match Lib_name.Map.find_exn p.entries name with
   | Library lib -> lib
   | _ -> assert false
diff --git a/src/dune/findlib/findlib.mli b/src/dune/findlib/findlib.mli
index 1e130079f12..de64220a65b 100644
--- a/src/dune/findlib/findlib.mli
+++ b/src/dune/findlib/findlib.mli
@@ -47,7 +47,7 @@ val all_packages : t -> Dune_package.Entry.t list
 val all_broken_packages : t -> (Package.Name.t * exn) list
 
 (** A dummy package. This is used to implement [external-lib-deps] *)
-val dummy_package : t -> name:Lib_name.t -> Dune_package.Lib.t
+val dummy_lib : t -> name:Lib_name.t -> Dune_package.Lib.t
 
 module Config : sig
   type t
diff --git a/src/dune/lib.ml b/src/dune/lib.ml
index dd1600198b0..7c73088b057 100644
--- a/src/dune/lib.ml
+++ b/src/dune/lib.ml
@@ -1840,7 +1840,7 @@ module DB = struct
           | Invalid_dune_package why -> Invalid why
           | Not_found ->
             if external_lib_deps_mode then
-              let pkg = Findlib.dummy_package findlib ~name in
+              let pkg = Findlib.dummy_lib findlib ~name in
               Found (Dune_package.Lib.info pkg)
             else
               Not_found ))
diff --git a/test/blackbox-tests/dune.inc b/test/blackbox-tests/dune.inc
index 083954266b1..d39f6f1624d 100644
--- a/test/blackbox-tests/dune.inc
+++ b/test/blackbox-tests/dune.inc
@@ -784,11 +784,21 @@
     (diff? run.t run.t.corrected)))))
 
 (rule
- (alias external-lib-deps)
- (deps (package dune) (source_tree test-cases/external-lib-deps))
+ (alias external-lib-deps-github3143)
+ (deps (package dune) (source_tree test-cases/external-lib-deps/github3143))
  (action
   (chdir
-   test-cases/external-lib-deps
+   test-cases/external-lib-deps/github3143
+   (progn
+    (run %{exe:cram.exe} run.t -sanitizer %{bin:sanitizer})
+    (diff? run.t run.t.corrected)))))
+
+(rule
+ (alias external-lib-deps-simple)
+ (deps (package dune) (source_tree test-cases/external-lib-deps/simple))
+ (action
+  (chdir
+   test-cases/external-lib-deps/simple
    (progn
     (run %{exe:cram.exe} run.t -sanitizer %{bin:sanitizer})
     (diff? run.t run.t.corrected)))))
@@ -2733,7 +2743,8 @@
   (alias exec-cmd)
   (alias exec-missing)
   (alias exes-with-c)
-  (alias external-lib-deps)
+  (alias external-lib-deps-github3143)
+  (alias external-lib-deps-simple)
   (alias extra-lang-line)
   (alias fallback-dune)
   (alias findlib)
@@ -2989,7 +3000,8 @@
   (alias exec-cmd)
   (alias exec-missing)
   (alias exes-with-c)
-  (alias external-lib-deps)
+  (alias external-lib-deps-github3143)
+  (alias external-lib-deps-simple)
   (alias extra-lang-line)
   (alias fallback-dune)
   (alias findlib)
diff --git a/test/blackbox-tests/test-cases/external-lib-deps/github3143/run.t b/test/blackbox-tests/test-cases/external-lib-deps/github3143/run.t
new file mode 100644
index 00000000000..2b4cbf68d1a
--- /dev/null
+++ b/test/blackbox-tests/test-cases/external-lib-deps/github3143/run.t
@@ -0,0 +1,13 @@
+Reproduce #3143
+
+  $ echo "(lang dune 2.3)" > dune-project
+  $ touch dummypkg.opam
+  $ cat >dune <<EOF
+  > (library
+  >  (public_name dummypkg)
+  >  (libraries base doesnotexist.foo))
+  > EOF
+  $ dune external-lib-deps @install
+  These are the external library dependencies in the default context:
+  - base
+  - doesnotexist.foo
diff --git a/test/blackbox-tests/test-cases/external-lib-deps/dune b/test/blackbox-tests/test-cases/external-lib-deps/simple/dune
similarity index 100%
rename from test/blackbox-tests/test-cases/external-lib-deps/dune
rename to test/blackbox-tests/test-cases/external-lib-deps/simple/dune
diff --git a/test/blackbox-tests/test-cases/external-lib-deps/dune-project b/test/blackbox-tests/test-cases/external-lib-deps/simple/dune-project
similarity index 100%
rename from test/blackbox-tests/test-cases/external-lib-deps/dune-project
rename to test/blackbox-tests/test-cases/external-lib-deps/simple/dune-project
diff --git a/test/blackbox-tests/test-cases/external-lib-deps/run.t b/test/blackbox-tests/test-cases/external-lib-deps/simple/run.t
similarity index 100%
rename from test/blackbox-tests/test-cases/external-lib-deps/run.t
rename to test/blackbox-tests/test-cases/external-lib-deps/simple/run.t