diff --git a/lib/hex/package.ex b/lib/hex/package.ex
index d112cb01..6565458e 100644
--- a/lib/hex/package.ex
+++ b/lib/hex/package.ex
@@ -44,7 +44,9 @@ defmodule Hex.Package do
         can include wildcards. Defaults to `#{inspect(default_files())}`.
       * `:exclude_patterns` - List of patterns matching files and directories to
         exclude from the package.
-      * `:licenses` - List of licenses used by the package.
+      * `:licenses` - List of licenses used by the package. Use SPDX license
+        identifiers or `LicenseRef-<idstring>` for custom licenses included in
+        the package.
       * `:links` - Map of links relevant to the package.
       * `:build_tools` - List of build tools that can build the package. Hex will
         try to automatically detect the build tools based on the files in the
diff --git a/src/mix_hex_licenses.erl b/src/mix_hex_licenses.erl
index 192f9091..def4ada5 100644
--- a/src/mix_hex_licenses.erl
+++ b/src/mix_hex_licenses.erl
@@ -1,4 +1,4 @@
-%% Vendored from hex_core v0.15.0 (90f9f59), do not edit manually
+%% Vendored from hex_core v0.15.0 (4ff8378), do not edit manually
 
 %% @doc
 %% Hex Licenses.
@@ -667,4 +667,30 @@ valid(<<"xlock">>) -> true;
 valid(<<"xpp">>) -> true;
 valid(<<"xzoom">>) -> true;
 valid(<<"zlib-acknowledgement">>) -> true;
+valid(<<"LicenseRef-", IdString/binary>>) -> valid_license_ref_idstring(IdString);
 valid(_) -> false.
+
+valid_license_ref_idstring(<<>>) ->
+    false;
+valid_license_ref_idstring(IdString) ->
+    valid_license_ref_idstring(IdString, true).
+
+valid_license_ref_idstring(<<>>, Valid) ->
+    Valid;
+valid_license_ref_idstring(_, false) ->
+    false;
+valid_license_ref_idstring(<<Char, Rest/binary>>, true) ->
+    valid_license_ref_idstring(Rest, valid_license_ref_char(Char)).
+
+valid_license_ref_char(Char) when Char >= $A, Char =< $Z ->
+    true;
+valid_license_ref_char(Char) when Char >= $a, Char =< $z ->
+    true;
+valid_license_ref_char(Char) when Char >= $0, Char =< $9 ->
+    true;
+valid_license_ref_char($-) ->
+    true;
+valid_license_ref_char($.) ->
+    true;
+valid_license_ref_char(_) ->
+    false.
diff --git a/test/mix/tasks/hex.build_test.exs b/test/mix/tasks/hex.build_test.exs
index 5c3a13c9..119beb58 100644
--- a/test/mix/tasks/hex.build_test.exs
+++ b/test/mix/tasks/hex.build_test.exs
@@ -13,6 +13,14 @@ defmodule Mix.Tasks.Hex.BuildTest do
       :mix_hex_erl_tar.extract({:binary, files[~c"contents.tar.gz"]}, [:compressed, cwd: path])
   end
 
+  test "vendored licenses accept custom LicenseRef identifiers" do
+    assert :mix_hex_licenses.valid("LicenseRef-Journey")
+    assert :mix_hex_licenses.valid("LicenseRef-acme.1-2")
+    refute :mix_hex_licenses.valid("LicenseRef-")
+    refute :mix_hex_licenses.valid("LicenseRef-Journey License")
+    refute :mix_hex_licenses.valid("LicenseRef-Journey_License")
+  end
+
   test "create" do
     Process.put(:hex_test_app_name, :build_app_name)
     Mix.Project.push(ReleaseSimple.MixProject)
@@ -66,6 +74,22 @@ defmodule Mix.Tasks.Hex.BuildTest do
     purge([ReleaseInvalidLicenses.MixProject])
   end
 
+  test "create with custom LicenseRef license" do
+    Process.put(:hex_test_app_name, :release_license_ref)
+    Mix.Project.push(ReleaseLicenseRef.MixProject)
+
+    in_tmp(fn ->
+      Hex.State.put(:cache_home, tmp_path())
+      File.write!("myfile.txt", "hello")
+      File.write!("LICENSE", "Journey License")
+      Mix.Tasks.Hex.Build.run([])
+
+      assert package_created?("release_license_ref-0.0.1")
+    end)
+  after
+    purge([ReleaseLicenseRef.MixProject])
+  end
+
   test "create private package with invalid licenses" do
     Process.put(:hex_test_app_name, :release_repo_invalid_licenses)
     Mix.Project.push(ReleaseRepoInvalidLicenses.MixProject)
diff --git a/test/support/release_samples.ex b/test/support/release_samples.ex
index 68e43f7e..94df2f4a 100644
--- a/test/support/release_samples.ex
+++ b/test/support/release_samples.ex
@@ -337,6 +337,21 @@ defmodule ReleaseInvalidLicenses.MixProject do
   end
 end
 
+defmodule ReleaseLicenseRef.MixProject do
+  def project do
+    [
+      app: :release_license_ref,
+      description: "Package with a custom license reference",
+      version: "0.0.1",
+      package: [
+        licenses: ["LicenseRef-Journey"],
+        files: ["myfile.txt", "LICENSE"],
+        links: %{"a" => "http://a"}
+      ]
+    ]
+  end
+end
+
 defmodule ReleaseAppFalseDep.MixProject do
   def project do
     [