diff --git a/lib/who_need_help_web/controllers/e2e_tile_controller.ex b/lib/who_need_help_web/controllers/e2e_tile_controller.ex
index 5de67ad..2246360 100644
--- a/lib/who_need_help_web/controllers/e2e_tile_controller.ex
+++ b/lib/who_need_help_web/controllers/e2e_tile_controller.ex
@@ -2,12 +2,12 @@ defmodule WhoNeedHelpWeb.E2eTileController do
   use WhoNeedHelpWeb, :controller
 
   @tile_png Base.decode64!(
-              "iVBORw0KGgoAAAANSUhEUgAAAQAAAAEAAQMAAABmvDolAAAAA1BMVEXu8vcBVSTwAAAAH0lEQVRo3u3BAQ0AAADCoPdPbQ43oAAAAAAAAAAAvg0hAAABfxmcpwAAAABJRU5ErkJggg=="
+              "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"
             )
 
   def show(conn, _params) do
     conn
-    |> put_resp_content_type("image/png")
+    |> put_resp_content_type("image/png", nil)
     |> put_resp_header("cache-control", "public, max-age=3600")
     |> send_resp(:ok, @tile_png)
   end
diff --git a/test/who_need_help_web/controllers/e2e_tile_controller_test.exs b/test/who_need_help_web/controllers/e2e_tile_controller_test.exs
new file mode 100644
index 0000000..34c57d3
--- /dev/null
+++ b/test/who_need_help_web/controllers/e2e_tile_controller_test.exs
@@ -0,0 +1,25 @@
+defmodule WhoNeedHelpWeb.E2eTileControllerTest do
+  use WhoNeedHelpWeb.ConnCase, async: true
+
+  test "serves a WebKit-compatible truecolor PNG without a text charset", %{conn: conn} do
+    conn = WhoNeedHelpWeb.E2eTileController.show(conn, %{})
+
+    assert response(conn, 200)
+    assert get_resp_header(conn, "content-type") == ["image/png"]
+    assert get_resp_header(conn, "cache-control") == ["public, max-age=3600"]
+
+    assert <<
+             0x89,
+             "PNG\r\n",
+             0x1A,
+             "\n",
+             13::32,
+             "IHDR",
+             256::32,
+             256::32,
+             8,
+             2,
+             _rest::binary
+           >> = conn.resp_body
+  end
+end