diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 5637d5bd..da9e13d4 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -19,7 +19,7 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - elixir: 1.19.5
+          - elixir: 1.20.3
             erlang: 27.3.4.10
     name: Elixir v${{ matrix.elixir }}, Erlang v${{ matrix.erlang }}
     steps:
diff --git a/mise.toml b/mise.toml
new file mode 100644
index 00000000..eef0642e
--- /dev/null
+++ b/mise.toml
@@ -0,0 +1,3 @@
+[tools]
+erlang = '27.3.4.10'
+elixir = '1.20.3-otp-27'