diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 5a7e6156..f55543a7 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -22,9 +22,9 @@ jobs:
           # One version down.
           - erlang: "27.2"
             elixir: "1.18"
-          # Oldest version. We technically support OTP 23 but hard to test in CI
+          # Oldest version.
           - erlang: "24.3"
-            elixir: "1.15"
+            elixir: "1.12.3"
 
     env:
       GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/lib/mint/application.ex b/lib/mint/application.ex
deleted file mode 100644
index 058d4a83..00000000
--- a/lib/mint/application.ex
+++ /dev/null
@@ -1,14 +0,0 @@
-defmodule Mint.Application do
-  @moduledoc false
-  use Application
-
-  def start(_type, _args) do
-    persistent_term =
-      Code.ensure_loaded?(:persistent_term) and function_exported?(:persistent_term, :get, 2)
-
-    Application.put_env(:mint, :persistent_term, persistent_term)
-
-    opts = [strategy: :one_for_one, name: Mint.Supervisor]
-    Supervisor.start_link([], opts)
-  end
-end
diff --git a/lib/mint/core/transport/ssl.ex b/lib/mint/core/transport/ssl.ex
index 8631bd75..d4cbf1b1 100644
--- a/lib/mint/core/transport/ssl.ex
+++ b/lib/mint/core/transport/ssl.ex
@@ -601,18 +601,14 @@ defmodule Mint.Core.Transport.SSL do
   end
 
   defp get_cacertfile(path) do
-    if Application.get_env(:mint, :persistent_term) do
-      case :persistent_term.get({:mint, {:cacertfile, path}}, :error) do
-        {:ok, cacerts} ->
-          cacerts
-
-        :error ->
-          cacerts = decode_cacertfile(path)
-          :persistent_term.put({:mint, {:cacertfile, path}}, {:ok, cacerts})
-          cacerts
-      end
-    else
-      decode_cacertfile(path)
+    case :persistent_term.get({:mint, {:cacertfile, path}}, :error) do
+      {:ok, cacerts} ->
+        cacerts
+
+      :error ->
+        cacerts = decode_cacertfile(path)
+        :persistent_term.put({:mint, {:cacertfile, path}}, {:ok, cacerts})
+        cacerts
     end
   end
 
diff --git a/lib/mint/http1.ex b/lib/mint/http1.ex
index be31db7c..5445ab60 100644
--- a/lib/mint/http1.ex
+++ b/lib/mint/http1.ex
@@ -762,7 +762,7 @@ defmodule Mint.HTTP1 do
         {:ok, conn, responses}
 
       length <= byte_size(data) ->
-        <<body::binary-size(^length), rest::binary>> = data
+        {body, rest} = :erlang.split_binary(data, length)
         {conn, responses} = add_body(conn, body, responses)
         conn = request_done(conn)
         responses = [{:done, request_ref} | responses]
@@ -836,7 +836,7 @@ defmodule Mint.HTTP1 do
         {:ok, conn, responses}
 
       length <= byte_size(data) ->
-        <<body::binary-size(^length), rest::binary>> = data
+        {body, rest} = :erlang.split_binary(data, length)
         {conn, responses} = add_body(conn, body, responses)
         conn = put_in(conn.request.body, {:chunked, :crlf})
         decode_body({:chunked, :crlf}, conn, rest, request_ref, responses)
diff --git a/lib/mint/http2.ex b/lib/mint/http2.ex
index dad9e506..d1b562d0 100644
--- a/lib/mint/http2.ex
+++ b/lib/mint/http2.ex
@@ -1266,7 +1266,7 @@ defmodule Mint.HTTP2 do
   end
 
   defp split_payload_in_chunks(binary, chunk_size, acc) do
-    <<chunk::size(^chunk_size)-binary, rest::binary>> = binary
+    {chunk, rest} = :erlang.split_binary(binary, chunk_size)
     split_payload_in_chunks(rest, chunk_size, [chunk | acc])
   end
 
diff --git a/lib/mint/http2/frame.ex b/lib/mint/http2/frame.ex
index 7312ee49..1b110580 100644
--- a/lib/mint/http2/frame.ex
+++ b/lib/mint/http2/frame.ex
@@ -271,7 +271,7 @@ defmodule Mint.HTTP2.Frame do
     else
       # 1 byte is for the space taken by pad_length
       data_length = byte_size(payload) - pad_length - 1
-      <<data::size(^data_length)-binary, padding::size(^pad_length)-binary>> = rest
+      {data, padding} = :erlang.split_binary(rest, data_length)
       {data, padding}
     end
   end
diff --git a/mix.exs b/mix.exs
index fce72a66..df67b1e1 100644
--- a/mix.exs
+++ b/mix.exs
@@ -8,7 +8,7 @@ defmodule Mint.MixProject do
     [
       app: :mint,
       version: @version,
-      elixir: "~> 1.15",
+      elixir: "~> 1.12",
       start_permanent: Mix.env() == :prod,
       elixirc_paths: elixirc_paths(Mix.env()),
       deps: deps(),
@@ -16,7 +16,6 @@ defmodule Mint.MixProject do
       # Xref
       xref: [
         exclude: [
-          :persistent_term,
           {:ssl, :cipher_suites, 1},
           {:public_key, :cacerts_get, 0},
           CAStore
@@ -54,8 +53,7 @@ defmodule Mint.MixProject do
   # Run "mix help compile.app" to learn about applications.
   def application do
     [
-      extra_applications: [:logger, :ssl],
-      mod: {Mint.Application, []}
+      extra_applications: [:logger, :ssl]
     ]
   end
 
diff --git a/test/mint/http1/conn_properties_test.exs b/test/mint/http1/conn_properties_test.exs
index 906c0038..2e1d7f27 100644
--- a/test/mint/http1/conn_properties_test.exs
+++ b/test/mint/http1/conn_properties_test.exs
@@ -90,7 +90,7 @@ defmodule Mint.HTTP1.PropertiesTest do
       |> Enum.sort()
       |> Enum.reduce({[], binary, 0}, fn split, {chunks, rest, prev_split} ->
         length = split - prev_split
-        <<chunk::binary-size(^length), rest::binary>> = rest
+        {chunk, rest} = :erlang.split_binary(rest, length)
         {[chunk | chunks], rest, split}
       end)
       |> join_last_chunk()