diff --git a/lib/lti_1p3/tool/launch_validation.ex b/lib/lti_1p3/tool/launch_validation.ex
index b27dc16..bc2ca1b 100644
--- a/lib/lti_1p3/tool/launch_validation.ex
+++ b/lib/lti_1p3/tool/launch_validation.ex
@@ -110,7 +110,8 @@ defmodule Lti_1p3.Tool.LaunchValidation do
 
   defp validate_message(jwt_body) do
     case jwt_body["https://purl.imsglobal.org/spec/lti/claim/message_type"] do
-      nil ->
+      # JOSE >= 1.11.12 decodes JSON null as the atom :null instead of nil
+      value when value == :null or is_nil(value) ->
         {:error, %{reason: :invalid_message_type, msg: "Missing message type"}}
 
       message_type ->
diff --git a/mix.exs b/mix.exs
index 1394fb8..390c06f 100644
--- a/mix.exs
+++ b/mix.exs
@@ -39,7 +39,7 @@ defmodule Lti_1p3.MixProject do
       {:ex_doc, "~> 0.28", only: :dev, runtime: false},
       {:httpoison, "~> 2.0"},
       {:jason, "~> 1.3"},
-      {:joken, "~> 2.2.0"},
+      {:joken, "~> 2.2"},
       {:mox, "~> 0.5", only: :test},
       {:timex, "~> 3.5"},
       {:uuid, "~> 1.1"}
diff --git a/mix.lock b/mix.lock
index 7c8e759..083cf60 100644
--- a/mix.lock
+++ b/mix.lock
@@ -14,8 +14,8 @@
   "httpoison": {:hex, :httpoison, "2.1.0", "655fd9a7b0b95ee3e9a3b535cf7ac8e08ef5229bab187fa86ac4208b122d934b", [:mix], [{:hackney, "~> 1.17", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "fc455cb4306b43827def4f57299b2d5ac8ac331cb23f517e734a4b78210a160c"},
   "idna": {:hex, :idna, "6.1.1", "8a63070e9f7d0c62eb9d9fcb360a7de382448200fbbd1b106cc96d3d8099df8d", [:rebar3], [{:unicode_util_compat, "~>0.7.0", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "92376eb7894412ed19ac475e4a86f7b413c1b9fbb5bd16dccd57934157944cea"},
   "jason": {:hex, :jason, "1.3.0", "fa6b82a934feb176263ad2df0dbd91bf633d4a46ebfdffea0c8ae82953714946", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "53fc1f51255390e0ec7e50f9cb41e751c260d065dcba2bf0d08dc51a4002c2ac"},
-  "joken": {:hex, :joken, "2.2.0", "2daa1b12be05184aff7b5ace1d43ca1f81345962285fff3f88db74927c954d3a", [:mix], [{:jose, "~> 1.9", [hex: :jose, repo: "hexpm", optional: false]}], "hexpm", "b4f92e30388206f869dd25d1af628a1d99d7586e5cf0672f64d4df84c4d2f5e9"},
-  "jose": {:hex, :jose, "1.11.1", "59da64010c69aad6cde2f5b9248b896b84472e99bd18f246085b7b9fe435dcdb", [:mix, :rebar3], [], "hexpm", "078f6c9fb3cd2f4cfafc972c814261a7d1e8d2b3685c0a76eb87e158efff1ac5"},
+  "joken": {:hex, :joken, "2.6.2", "5daaf82259ca603af4f0b065475099ada1b2b849ff140ccd37f4b6828ca6892a", [:mix], [{:jose, "~> 1.11.10", [hex: :jose, repo: "hexpm", optional: false]}], "hexpm", "5134b5b0a6e37494e46dbf9e4dad53808e5e787904b7c73972651b51cce3d72b"},
+  "jose": {:hex, :jose, "1.11.12", "06e62b467b61d3726cbc19e9b5489f7549c37993de846dfb3ee8259f9ed208b3", [:mix, :rebar3], [], "hexpm", "31e92b653e9210b696765cdd885437457de1add2a9011d92f8cf63e4641bab7b"},
   "makeup": {:hex, :makeup, "1.1.0", "6b67c8bc2882a6b6a445859952a602afc1a41c2e08379ca057c0f525366fc3ca", [:mix], [{:nimble_parsec, "~> 1.2.2 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "0a45ed501f4a8897f580eabf99a2e5234ea3e75a4373c8a52824f6e873be57a6"},
   "makeup_elixir": {:hex, :makeup_elixir, "0.16.0", "f8c570a0d33f8039513fbccaf7108c5d750f47d8defd44088371191b76492b0b", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "28b2cbdc13960a46ae9a8858c4bebdec3c9a6d7b4b9e7f4ed1502f8159f338e7"},
   "makeup_erlang": {:hex, :makeup_erlang, "0.1.1", "3fcb7f09eb9d98dc4d208f49cc955a34218fc41ff6b84df7c75b3e6e533cc65f", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "174d0809e98a4ef0b3309256cbf97101c6ec01c4ab0b23e926a9e17df2077cbb"},