diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ff1a524..aee78b1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -5,28 +5,50 @@ on:
       - main
 
 jobs:
-  test:
+  main:
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
-        elixir-version: [1.16, 1.15]
-        otp-version: [26, 25, 24]
+        include:
+          - elixir_version: '1.17'
+            otp_version: '27.0'
+            lint: true
+          - elixir_version: '1.17'
+            otp_version: '27.0'
+            req_0_4: true
+          - elixir_version: '1.16'
+            otp_version: '26.2.5'
+          - elixir_version: '1.16'
+            otp_version: '26.2.5'
+            req_0_4: true
+          - elixir_version: '1.15'
+            otp_version: '25.3.2.12'
+          - elixir_version: '1.15'
+            otp_version: '25.3.2.12'
+            req_0_4: true
 
-    name: Tests
+    name: Elixir ${{ matrix.elixir_version}} - OTP ${{ matrix.otp_version }} ${{ matrix.lint && '- Lint' }} ${{ matrix.req_0_4 && '- Req 0.4' }}
 
     steps:
       - uses: actions/checkout@v4
       - uses: erlef/setup-beam@v1
         with:
-          elixir-version: ${{ matrix.elixir-version }}
-          otp-version: ${{ matrix.otp-version }}
+          elixir-version: ${{ matrix.elixir_version }}
+          otp-version: ${{ matrix.otp_version }}
 
-      - run: mix deps.get
+      - run: cp blend/req_0_4.mix.lock mix.lock
+        if: ${{ matrix.req_0_4 }}
+
+      - run: mix deps.get --check-locked
 
       - run: mix compile --warnings-as-errors
-        if: matrix.elixir-version == 1.16 && matrix.otp-version == 26
+        if: ${{ matrix.lint }}
 
       - run: mix format --check-formatted
-        if: matrix.elixir-version == 1.16 && matrix.otp-version == 26
+        if: ${{ matrix.lint }}
+
+      - run: mix deps.unlock --check-unused
+        if: ${{ matrix.lint }}
 
       - run: mix test
diff --git a/.gitignore b/.gitignore
index 0c95af8..09d4c79 100644
--- a/.gitignore
+++ b/.gitignore
@@ -24,3 +24,7 @@ curl_req-*.tar
 
 # Temporary files, for example, from tests.
 /tmp/
+
+# blend library
+/blend/_build
+/blend/deps
diff --git a/blend.exs b/blend.exs
new file mode 100644
index 0000000..46f675b
--- /dev/null
+++ b/blend.exs
@@ -0,0 +1,4 @@
+# Example for testing against 1.x and 2.x of some dependency
+%{
+  req_0_4: [{:req, "~> 0.4.0"}]
+}
diff --git a/blend/req_0_4.mix.lock b/blend/req_0_4.mix.lock
new file mode 100644
index 0000000..06313f9
--- /dev/null
+++ b/blend/req_0_4.mix.lock
@@ -0,0 +1,19 @@
+%{
+  "blend": {:hex, :blend, "0.4.1", "d81d39a1b98dddc91dd465d0d6381bc5029c02a9c2018a568f62bb55efd1f64e", [:mix], [], "hexpm", "75c9f391456fa648e973e85c86e5bb4ea9bb1d3750b7b71967e0662e837001ab"},
+  "earmark_parser": {:hex, :earmark_parser, "1.4.41", "ab34711c9dc6212dda44fcd20ecb87ac3f3fce6f0ca2f28d4a00e4154f8cd599", [:mix], [], "hexpm", "a81a04c7e34b6617c2792e291b5a2e57ab316365c2644ddc553bb9ed863ebefa"},
+  "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"},
+  "finch": {:hex, :finch, "0.19.0", "c644641491ea854fc5c1bbaef36bfc764e3f08e7185e1f084e35e0672241b76d", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:mint, "~> 1.6.2 or ~> 1.7", [hex: :mint, repo: "hexpm", optional: false]}, {:nimble_options, "~> 0.4 or ~> 1.0", [hex: :nimble_options, repo: "hexpm", optional: false]}, {:nimble_pool, "~> 1.1", [hex: :nimble_pool, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "fc5324ce209125d1e2fa0fcd2634601c52a787aff1cd33ee833664a5af4ea2b6"},
+  "hpax": {:hex, :hpax, "1.0.0", "28dcf54509fe2152a3d040e4e3df5b265dcb6cb532029ecbacf4ce52caea3fd2", [:mix], [], "hexpm", "7f1314731d711e2ca5fdc7fd361296593fc2542570b3105595bb0bc6d0fad601"},
+  "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, "1.2.1", "e90ac1c65589ef354378def3ba19d401e739ee7ee06fb47f94c687016e3713d1", [:mix], [{:nimble_parsec, "~> 1.4", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "d36484867b0bae0fea568d10131197a4c2e47056a6fbe84922bf6ba71c8d17ce"},
+  "makeup_elixir": {:hex, :makeup_elixir, "1.0.0", "74bb8348c9b3a51d5c589bf5aebb0466a84b33274150e3b6ece1da45584afc82", [: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", "49159b7d7d999e836bedaf09dcf35ca18b312230cf901b725a64f3f42e407983"},
+  "makeup_erlang": {:hex, :makeup_erlang, "1.0.1", "c7f58c120b2b5aa5fd80d540a89fdf866ed42f1f3994e4fe189abebeab610839", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "8a89a1eeccc2d798d6ea15496a6e4870b75e014d1af514b1b71fa33134f57814"},
+  "mime": {:hex, :mime, "2.0.6", "8f18486773d9b15f95f4f4f1e39b710045fa1de891fada4516559967276e4dc2", [:mix], [], "hexpm", "c9945363a6b26d747389aac3643f8e0e09d30499a138ad64fe8fd1d13d9b153e"},
+  "mint": {:hex, :mint, "1.6.2", "af6d97a4051eee4f05b5500671d47c3a67dac7386045d87a904126fd4bbcea2e", [:mix], [{:castore, "~> 0.1.0 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:hpax, "~> 0.1.1 or ~> 0.2.0 or ~> 1.0", [hex: :hpax, repo: "hexpm", optional: false]}], "hexpm", "5ee441dffc1892f1ae59127f74afe8fd82fda6587794278d924e4d90ea3d63f9"},
+  "nimble_options": {:hex, :nimble_options, "1.1.1", "e3a492d54d85fc3fd7c5baf411d9d2852922f66e69476317787a7b2bb000a61b", [:mix], [], "hexpm", "821b2470ca9442c4b6984882fe9bb0389371b8ddec4d45a9504f00a66f650b44"},
+  "nimble_ownership": {:hex, :nimble_ownership, "0.3.2", "d4fa4056ade0ae33b5a9eb64554a1b3779689282e37513260125d2d6b32e4874", [:mix], [], "hexpm", "28b9a9f4094fda1aa8ca72f732ff3223eb54aa3eda4fed9022254de2c152b138"},
+  "nimble_parsec": {:hex, :nimble_parsec, "1.4.0", "51f9b613ea62cfa97b25ccc2c1b4216e81df970acd8e16e8d1bdc58fef21370d", [:mix], [], "hexpm", "9c565862810fb383e9838c1dd2d7d2c437b3d13b267414ba6af33e50d2d1cf28"},
+  "nimble_pool": {:hex, :nimble_pool, "1.1.0", "bf9c29fbdcba3564a8b800d1eeb5a3c58f36e1e11d7b7fb2e084a643f645f06b", [:mix], [], "hexpm", "af2e4e6b34197db81f7aad230c1118eac993acc0dae6bc83bac0126d4ae0813a"},
+  "req": {:hex, :req, "0.4.14", "103de133a076a31044e5458e0f850d5681eef23dfabf3ea34af63212e3b902e2", [:mix], [{:aws_signature, "~> 0.3.2", [hex: :aws_signature, repo: "hexpm", optional: true]}, {:brotli, "~> 0.3.1", [hex: :brotli, repo: "hexpm", optional: true]}, {:ezstd, "~> 1.0", [hex: :ezstd, repo: "hexpm", optional: true]}, {:finch, "~> 0.17", [hex: :finch, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}, {:mime, "~> 1.6 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:nimble_csv, "~> 1.0", [hex: :nimble_csv, repo: "hexpm", optional: true]}, {:nimble_ownership, "~> 0.2.0 or ~> 0.3.0", [hex: :nimble_ownership, repo: "hexpm", optional: false]}, {:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm", "2ddd3d33f9ab714ced8d3c15fd03db40c14dbf129003c4a3eb80fac2cc0b1b08"},
+  "telemetry": {:hex, :telemetry, "1.3.0", "fedebbae410d715cf8e7062c96a1ef32ec22e764197f70cda73d82778d61e7a2", [:rebar3], [], "hexpm", "7015fc8919dbe63764f4b4b87a95b7c0996bd539e0d499be6ec9d7f3875b79e6"},
+}
diff --git a/mix.exs b/mix.exs
index f77f138..c768f9b 100644
--- a/mix.exs
+++ b/mix.exs
@@ -26,7 +26,8 @@ defmodule CurlReq.MixProject do
   defp deps do
     [
       {:req, "~> 0.4.0 or ~> 0.5.0"},
-      {:ex_doc, ">= 0.0.0", only: :dev}
+      {:ex_doc, ">= 0.0.0", only: :dev},
+      {:blend, "~> 0.4.1", only: :dev}
     ]
   end
 
diff --git a/mix.lock b/mix.lock
index 2f49764..a2d7685 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,4 +1,5 @@
 %{
+  "blend": {:hex, :blend, "0.4.1", "d81d39a1b98dddc91dd465d0d6381bc5029c02a9c2018a568f62bb55efd1f64e", [:mix], [], "hexpm", "75c9f391456fa648e973e85c86e5bb4ea9bb1d3750b7b71967e0662e837001ab"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.41", "ab34711c9dc6212dda44fcd20ecb87ac3f3fce6f0ca2f28d4a00e4154f8cd599", [:mix], [], "hexpm", "a81a04c7e34b6617c2792e291b5a2e57ab316365c2644ddc553bb9ed863ebefa"},
   "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"},
   "finch": {:hex, :finch, "0.19.0", "c644641491ea854fc5c1bbaef36bfc764e3f08e7185e1f084e35e0672241b76d", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:mint, "~> 1.6.2 or ~> 1.7", [hex: :mint, repo: "hexpm", optional: false]}, {:nimble_options, "~> 0.4 or ~> 1.0", [hex: :nimble_options, repo: "hexpm", optional: false]}, {:nimble_pool, "~> 1.1", [hex: :nimble_pool, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "fc5324ce209125d1e2fa0fcd2634601c52a787aff1cd33ee833664a5af4ea2b6"},