diff --git a/CHANGELOG.md b/CHANGELOG.md
index 521d8dccd..29f54c653 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,14 @@
 
 ## Cldr v2.40.1
 
+This is the changelog for Cldr v2.40.2 released on December 23rd, 2024.  For older changelogs please consult the release tag on [GitHub](https://github.com/elixir-cldr/cldr/tags)
+
+### Bug Fixes
+
+* Support (and automatically configure) Elixir 1.18's JSON module as a `:json_library` in the global configuration. Thanks to @Neophen for the report. Closes #147.
+
+## Cldr v2.40.1
+
 This is the changelog for Cldr v2.40.1 released on August 16th, 2024.  For older changelogs please consult the release tag on [GitHub](https://github.com/elixir-cldr/cldr/tags)
 
 ### Bug Fixes
diff --git a/README.md b/README.md
index c0655f776..22218e950 100644
--- a/README.md
+++ b/README.md
@@ -6,15 +6,12 @@
 [![Hex.pm](https://img.shields.io/hexpm/dt/ex_cldr.svg?)](https://hex.pm/packages/ex_cldr)
 [![Hex.pm](https://img.shields.io/hexpm/l/ex_cldr.svg)](https://hex.pm/packages/ex_cldr)
 
-> #### `Change to :json_library configuration` {: .warning}
->
+> #### Change to :json_library configuration {: .warning}
 > As of `ex_cldr` version 2.37.2 the configuration parameter `:json_library`
 > does not attempt to read the configuration of either Phoenix or Ecto.
->
-> Specifying the `:json_library` parameter under the `:ex_cldr`
-> configuration key in `config.exs` is recommended when executing on OTP
-> versions below OTP 27 but the availability of `Jason` or `Poison` will still be
-> automatically detected and configured if the `:json_library` key is not set.
+
+> #### Automatic configuration of :json_library  {: .info}
+> OTP 27 and Elixir 1.18 both include native JSON libraries. Therefore if running on either (or both) of these platforms, no `:json_library` configuration is required or recommended.
 
 ## Introduction
 
@@ -207,9 +204,12 @@ config :ex_cldr,
 
 Note that the `:json_library` key can only be defined at the global level since it is required during compilation before any backend module is compiled.
 
+> #### Automatic configuration of :json_library  {: .info}
+> OTP 27 and Elixir 1.18 both include native JSON libraries. Therefore if running on either (or both) of these platforms, no `:json_library` configuration is required or recommended.
+
 On most platforms other than Windows the `:cacertfile` will be automatically detected. Any configured `:cacertfile` will take precedence on all platforms.
 
-**If configuration beyond the keys `:default_locale`, `:cacertfile` or `:json_library` is defined a deprecation warning is printed at compile time noting that configuration should be moved to a backend module.**
+**If configuration beyond the keys `:default_locale`, `:cacertfile` or `:json_library` are defined a deprecation warning is printed at compile time noting that configuration should be moved to a backend module.**
 
 ### Configuration Priority
 
diff --git a/lib/cldr/config/config.ex b/lib/cldr/config/config.ex
index 9be053ea7..754d2b375 100644
--- a/lib/cldr/config/config.ex
+++ b/lib/cldr/config/config.ex
@@ -139,12 +139,12 @@ defmodule Cldr.Config do
     @app_name
   end
 
-  # This wrapper module doesn't produce compatible ressults - yet!
   json = if(Code.ensure_loaded?(Cldr.Json), do: Cldr.Json, else: nil)
+  elixir_json = if(Code.ensure_loaded?(JSON), do: JSON, else: nil)
   poison = if(Code.ensure_loaded?(Poison), do: Poison, else: nil)
   jason = if(Code.ensure_loaded?(Jason), do: Jason, else: nil)
   cldr_json = Application.compile_env(:ex_cldr, :json_library)
-  @json_lib cldr_json || json || jason || poison
+  @json_lib cldr_json || json || elixir_json || jason || poison
 
   cond do
     Code.ensure_loaded?(@json_lib) and function_exported?(@json_lib, :decode!, 1) ->
@@ -2100,7 +2100,8 @@ defmodule Cldr.Config do
       cldr_data_dir()
       |> Path.join(@units_file)
       |> File.read!()
-      |> json_library().decode!(keys: :atoms)
+      |> json_library().decode!()
+      |> Cldr.Map.atomize_keys()
 
     base_units =
       data.base_units
@@ -2256,7 +2257,8 @@ defmodule Cldr.Config do
     cldr_data_dir()
     |> Path.join(@calendar_preferences_file)
     |> File.read!()
-    |> json_library().decode!(keys: :atoms)
+    |> json_library().decode!()
+    |> Cldr.Map.atomize_keys()
     |> Cldr.Map.atomize_values()
   end
 
diff --git a/mix.exs b/mix.exs
index 4b98d307f..c88f41431 100644
--- a/mix.exs
+++ b/mix.exs
@@ -1,7 +1,7 @@
 defmodule Cldr.Mixfile do
   use Mix.Project
 
-  @version "2.40.1"
+  @version "2.40.2"
 
   def project do
     [
diff --git a/mix.lock b/mix.lock
index 41f5ccc23..665208703 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,20 +1,20 @@
 %{
   "benchee": {:hex, :benchee, "1.3.1", "c786e6a76321121a44229dde3988fc772bca73ea75170a73fd5f4ddf1af95ccf", [:mix], [{:deep_merge, "~> 1.0", [hex: :deep_merge, repo: "hexpm", optional: false]}, {:statistex, "~> 1.0", [hex: :statistex, repo: "hexpm", optional: false]}, {:table, "~> 0.1.0", [hex: :table, repo: "hexpm", optional: true]}], "hexpm", "76224c58ea1d0391c8309a8ecbfe27d71062878f59bd41a390266bf4ac1cc56d"},
-  "cldr_utils": {:hex, :cldr_utils, "2.28.1", "3d85c835e1d0b7bceb9feed1647025ff7df59180246f13b582422f12b1afd52c", [:mix], [{:castore, "~> 0.1 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:certifi, "~> 2.5", [hex: :certifi, repo: "hexpm", optional: true]}, {:decimal, "~> 1.9 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}], "hexpm", "79a5f645481d09b1372962384aa275d67d69273e73e3b38a9fee363eb57c2b79"},
-  "decimal": {:hex, :decimal, "2.1.1", "5611dca5d4b2c3dd497dec8f68751f1f1a54755e8ed2a966c2633cf885973ad6", [:mix], [], "hexpm", "53cfe5f497ed0e7771ae1a475575603d77425099ba5faef9394932b35020ffcc"},
+  "cldr_utils": {:hex, :cldr_utils, "2.28.2", "f500667164a9043369071e4f9dcef31f88b8589b2e2c07a1eb9f9fa53cb1dce9", [:mix], [{:castore, "~> 0.1 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:certifi, "~> 2.5", [hex: :certifi, repo: "hexpm", optional: true]}, {:decimal, "~> 1.9 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}], "hexpm", "c506eb1a170ba7cdca59b304ba02a56795ed119856662f6b1a420af80ec42551"},
+  "decimal": {:hex, :decimal, "2.3.0", "3ad6255aa77b4a3c4f818171b12d237500e63525c2fd056699967a3e7ea20f62", [:mix], [], "hexpm", "a4d66355cb29cb47c3cf30e71329e58361cfcb37c34235ef3bf1d7bf3773aeac"},
   "deep_merge": {:hex, :deep_merge, "1.0.0", "b4aa1a0d1acac393bdf38b2291af38cb1d4a52806cf7a4906f718e1feb5ee961", [:mix], [], "hexpm", "ce708e5f094b9cd4e8f2be4f00d2f4250c4095be93f8cd6d018c753894885430"},
-  "dialyxir": {:hex, :dialyxir, "1.4.3", "edd0124f358f0b9e95bfe53a9fcf806d615d8f838e2202a9f430d59566b6b53b", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "bf2cfb75cd5c5006bec30141b131663299c661a864ec7fbbc72dfa557487a986"},
-  "earmark_parser": {:hex, :earmark_parser, "1.4.41", "ab34711c9dc6212dda44fcd20ecb87ac3f3fce6f0ca2f28d4a00e4154f8cd599", [:mix], [], "hexpm", "a81a04c7e34b6617c2792e291b5a2e57ab316365c2644ddc553bb9ed863ebefa"},
+  "dialyxir": {:hex, :dialyxir, "1.4.5", "ca1571ac18e0f88d4ab245f0b60fa31ff1b12cbae2b11bd25d207f865e8ae78a", [:mix], [{:erlex, ">= 0.2.7", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "b0fb08bb8107c750db5c0b324fa2df5ceaa0f9307690ee3c1f6ba5b9eb5d35c3"},
+  "earmark_parser": {:hex, :earmark_parser, "1.4.42", "f23d856f41919f17cd06a493923a722d87a2d684f143a1e663c04a2b93100682", [:mix], [], "hexpm", "6915b6ca369b5f7346636a2f41c6a6d78b5af419d61a611079189233358b8b8b"},
   "erlex": {:hex, :erlex, "0.2.7", "810e8725f96ab74d17aac676e748627a07bc87eb950d2b83acd29dc047a30595", [:mix], [], "hexpm", "3ed95f79d1a844c3f6bf0cea61e0d5612a42ce56da9c03f01df538685365efb0"},
-  "ex_doc": {:hex, :ex_doc, "0.34.2", "13eedf3844ccdce25cfd837b99bea9ad92c4e511233199440488d217c92571e8", [:mix], [{:earmark_parser, "~> 1.4.39", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.0", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14 or ~> 1.0", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1 or ~> 1.0", [hex: :makeup_erlang, repo: "hexpm", optional: false]}, {:makeup_html, ">= 0.1.0", [hex: :makeup_html, repo: "hexpm", optional: true]}], "hexpm", "5ce5f16b41208a50106afed3de6a2ed34f4acfd65715b82a0b84b49d995f95c1"},
-  "expo": {:hex, :expo, "1.0.0", "647639267e088717232f4d4451526e7a9de31a3402af7fcbda09b27e9a10395a", [:mix], [], "hexpm", "18d2093d344d97678e8a331ca0391e85d29816f9664a25653fd7e6166827827c"},
-  "gettext": {:hex, :gettext, "0.26.1", "38e14ea5dcf962d1fc9f361b63ea07c0ce715a8ef1f9e82d3dfb8e67e0416715", [:mix], [{:expo, "~> 0.5.1 or ~> 1.0", [hex: :expo, repo: "hexpm", optional: false]}], "hexpm", "01ce56f188b9dc28780a52783d6529ad2bc7124f9744e571e1ee4ea88bf08734"},
+  "ex_doc": {:hex, :ex_doc, "0.35.1", "de804c590d3df2d9d5b8aec77d758b00c814b356119b3d4455e4b8a8687aecaf", [:mix], [{:earmark_parser, "~> 1.4.39", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.0", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14 or ~> 1.0", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1 or ~> 1.0", [hex: :makeup_erlang, repo: "hexpm", optional: false]}, {:makeup_html, ">= 0.1.0", [hex: :makeup_html, repo: "hexpm", optional: true]}], "hexpm", "2121c6402c8d44b05622677b761371a759143b958c6c19f6558ff64d0aed40df"},
+  "expo": {:hex, :expo, "1.1.0", "f7b9ed7fb5745ebe1eeedf3d6f29226c5dd52897ac67c0f8af62a07e661e5c75", [:mix], [], "hexpm", "fbadf93f4700fb44c331362177bdca9eeb8097e8b0ef525c9cc501cb9917c960"},
+  "gettext": {:hex, :gettext, "0.26.2", "5978aa7b21fada6deabf1f6341ddba50bc69c999e812211903b169799208f2a8", [:mix], [{:expo, "~> 0.5.1 or ~> 1.0", [hex: :expo, repo: "hexpm", optional: false]}], "hexpm", "aa978504bcf76511efdc22d580ba08e2279caab1066b76bb9aa81c4a1e0a32a5"},
   "jason": {:hex, :jason, "1.4.4", "b9226785a9aa77b6857ca22832cffa5d5011a667207eb2a0ad56adb5db443b8a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "c5eb0cab91f094599f94d55bc63409236a8ec69a21a67814529e8d5f6cc90b3b"},
-  "makeup": {:hex, :makeup, "1.1.2", "9ba8837913bdf757787e71c1581c21f9d2455f4dd04cfca785c70bbfff1a76a3", [:mix], [{:nimble_parsec, "~> 1.2.2 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "cce1566b81fbcbd21eca8ffe808f33b221f9eee2cbc7a1706fc3da9ff18e6cac"},
-  "makeup_elixir": {:hex, :makeup_elixir, "0.16.2", "627e84b8e8bf22e60a2579dad15067c755531fea049ae26ef1020cad58fe9578", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "41193978704763f6bbe6cc2758b84909e62984c7752b3784bd3c218bb341706b"},
+  "makeup": {:hex, :makeup, "1.2.1", "e90ac1c65589ef354378def3ba19d401e739ee7ee06fb47f94c687016e3713d1", [:mix], [{:nimble_parsec, "~> 1.4", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "d36484867b0bae0fea568d10131197a4c2e47056a6fbe84922bf6ba71c8d17ce"},
+  "makeup_elixir": {:hex, :makeup_elixir, "1.0.1", "e928a4f984e795e41e3abd27bfc09f51db16ab8ba1aebdba2b3a575437efafc2", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "7284900d412a3e5cfd97fdaed4f5ed389b8f2b4cb49efc0eb3bd10e2febf9507"},
   "makeup_erlang": {:hex, :makeup_erlang, "1.0.1", "c7f58c120b2b5aa5fd80d540a89fdf866ed42f1f3994e4fe189abebeab610839", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "8a89a1eeccc2d798d6ea15496a6e4870b75e014d1af514b1b71fa33134f57814"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.4.0", "51f9b613ea62cfa97b25ccc2c1b4216e81df970acd8e16e8d1bdc58fef21370d", [:mix], [], "hexpm", "9c565862810fb383e9838c1dd2d7d2c437b3d13b267414ba6af33e50d2d1cf28"},
   "statistex": {:hex, :statistex, "1.0.0", "f3dc93f3c0c6c92e5f291704cf62b99b553253d7969e9a5fa713e5481cd858a5", [:mix], [], "hexpm", "ff9d8bee7035028ab4742ff52fc80a2aa35cece833cf5319009b52f1b5a86c27"},
-  "stream_data": {:hex, :stream_data, "1.1.1", "fd515ca95619cca83ba08b20f5e814aaf1e5ebff114659dc9731f966c9226246", [:mix], [], "hexpm", "45d0cd46bd06738463fd53f22b70042dbb58c384bb99ef4e7576e7bb7d3b8c8c"},
+  "stream_data": {:hex, :stream_data, "1.1.2", "05499eaec0443349ff877aaabc6e194e82bda6799b9ce6aaa1aadac15a9fdb4d", [:mix], [], "hexpm", "129558d2c77cbc1eb2f4747acbbea79e181a5da51108457000020a906813a1a9"},
   "sweet_xml": {:hex, :sweet_xml, "0.7.4", "a8b7e1ce7ecd775c7e8a65d501bc2cd933bff3a9c41ab763f5105688ef485d08", [:mix], [], "hexpm", "e7c4b0bdbf460c928234951def54fe87edf1a170f6896675443279e2dbeba167"},
 }
diff --git a/mix/dev_helpers.ex b/mix/dev_helpers.ex
index f8d3bdbe5..c6f3d79ed 100644
--- a/mix/dev_helpers.ex
+++ b/mix/dev_helpers.ex
@@ -4,6 +4,7 @@ defmodule Cldr.DevHelpers do
   In CLDR 46 there are only :standard and :us
 
   """
+  @dialyzer {:nowarn_function, [known_separator_types: 0]}
   def known_separator_types do
     config = %Cldr.Config{locales: :all}
     locales = Cldr.Locale.Loader.known_locale_names(config)