diff --git a/mix.exs b/mix.exs
index e35e973..65d9552 100644
--- a/mix.exs
+++ b/mix.exs
@@ -31,7 +31,7 @@ defmodule Sprites.MixProject do
       {:req, "~> 0.5"},
       {:gun, "~> 2.1"},
       # Cowlib 2.20 requires OTP 27; keep compatibility with Elixir 1.15 / OTP 26.
-      {:cowlib, "~> 2.19.0"},
+      {:cowlib, "~> 2.21.0"},
       {:jason, "~> 1.4"},
       {:client_signals, "~> 0.5.0"},
       {:plug, "~> 1.0", only: :test},
diff --git a/mix.lock b/mix.lock
index 1377029..c05ff67 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,7 +1,7 @@
 %{
   "castore": {:hex, :castore, "1.0.17", "4f9770d2d45fbd91dcf6bd404cf64e7e58fed04fadda0923dc32acca0badffa2", [:mix], [], "hexpm", "12d24b9d80b910dd3953e165636d68f147a31db945d2dcb9365e441f8b5351e5"},
   "client_signals": {:hex, :client_signals, "0.5.0", "7705cfd5652609f1cab1a8728e4ee28dba38ecaf13b59daa294865e09fa1bdad", [:mix], [{:opentelemetry_api, "~> 1.4", [hex: :opentelemetry_api, repo: "hexpm", optional: true]}, {:plug, "~> 1.14", [hex: :plug, repo: "hexpm", optional: true]}, {:prom_ex, "~> 1.11", [hex: :prom_ex, repo: "hexpm", optional: true]}, {:telemetry, "~> 1.0", [hex: :telemetry, repo: "hexpm", optional: true]}], "hexpm", "263ca9442f4534b0aa5d846f29d532ad693a3cb50aae0ddba1f3d6c8ebded566"},
-  "cowlib": {:hex, :cowlib, "2.19.0", "c9d11c9d035472e27a740c9f327786c61ed209269b4be0260d59d3ec07b8949f", [:make, :rebar3], [], "hexpm", "6dc66e3135b229193ea4dcb14294e79520c923d391315c9c962ef0b4bea72356"},
+  "cowlib": {:hex, :cowlib, "2.21.0", "3ea757c79784bdbdebac7857ce3adf2290af6b8680d4248c75e40ced2e98c89e", [:make, :rebar3], [], "hexpm", "0960248773762a5319b3c17285028bc76f54f58ef0f9451367401bdf67b46274"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.46", "67607a0532e810c6f630a515c548d0b24949643f168cc556303bee4cf96105c7", [:mix], [], "hexpm", "9c44636e8a1c68c62f526b2dcd85d941dbbcee7ab82cf64ba06ce28bef8e89f5"},
   "ex_doc": {:hex, :ex_doc, "0.40.4", "66f2e42bf588594d5a8aab31cad87f2ddad09d0da1b1a2f379340ec2c2e497cb", [:mix], [{:earmark_parser, "~> 1.4.46", [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", "6222b9e423d76584ee34df2c82a5ed72c2d53dc153f7f483ad28b378694186cc"},
   "finch": {:hex, :finch, "0.24.0", "4022b6194e907b6d9b597c168001cac38e488a35fe36cef9d8297e3159782510", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:mint, "~> 1.8", [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", "33ba40069c3587c2f99f9125b766e19dad87d6d54be3c6961db2304df04cef00"},