diff --git a/changelog.md b/changelog.md
index ca8ea39..af80d9f 100644
--- a/changelog.md
+++ b/changelog.md
@@ -7,6 +7,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Removed
+
+* Stop bundling the Linaro UEFI firmware for ARM64. `linaro_uefi.fd` is no
+  longer part of the `qemu-system-aarch64` tarball. Its only consumer, OpenBSD
+  ARM64, now boots on the shared edk2 `uefi.fd` with ACPI disabled
+  ([cross-platform-actions/action#160](https://github.com/cross-platform-actions/action/pull/160)).
+  The Linaro release server it was downloaded from has been retired and
+  redirects to a landing page, so 1.1.0 shipped an HTML page in its place
+
+### Fixed
+
+* Fail the build when a download returns an unsuccessful HTTP status or an HTML
+  document instead of the requested file
+* Verify the contents of the bundled firmware files, not only their presence
+
 ## [1.1.0] - 2026-07-26
 
 ### Added
diff --git a/ci.rb b/ci.rb
index 504d07d..4680e7e 100755
--- a/ci.rb
+++ b/ci.rb
@@ -120,8 +120,6 @@ def bundle_uefi
       File.open(uefi_target_path, File::RDWR) do |file|
         file.truncate(file.read.bytes.rindex { _1 != 0 })
       end
-
-      bundle_linaro_uefi
     end
 
     private
@@ -141,19 +139,6 @@ def unpack_uefi
       FileUtils.rm_f uefi_source_path
       unpack_bzip2 archive
     end
-
-    def bundle_linaro_uefi
-      download_file(linaro_uefi_url, linaro_uefi_target_path)
-    end
-
-    def linaro_uefi_url
-      "https://releases.linaro.org/components/kernel/uefi-linaro/latest/release/qemu64/QEMU_EFI.fd"
-    end
-
-    def linaro_uefi_target_path
-      @linaro_uefi_target_path ||=
-        File.join(firmware_target_directory, "linaro_uefi.fd")
-    end
   end
 
   class Riscv64 < Architecture
@@ -583,12 +568,34 @@ def execute(*args, env: {})
   Kernel.system env, *args, exception: true
 end
 
+HTML_CONTENT_TYPES = %w[text/html application/xhtml+xml].freeze
+
+HTML_SIGNATURE = /\A\s*<(?:!doctype\s+html|html[\s>])/i
+
+# Downloads a file, refusing to write anything but the requested payload. A
+# retired host that redirects to a landing page answers with a successful
+# status and an HTML body, which would otherwise silently be bundled as if it
+# were the expected file.
 def download_file(url, destination)
-  URI.open(url) do |uri|
-    File.open(destination, 'w') { _1.write(uri.read) }
+  URI.open(url) do |io|
+    content = io.read
+    validate_download(url, io, content)
+    File.binwrite(destination, content)
   end
 end
 
+def validate_download(url, io, content)
+  raise "Failed to download #{url}: HTTP #{Array(io.status).join(' ')}" unless successful_response?(io)
+  raise "Failed to download #{url}: expected a file, got an HTML document" if html?(io, content)
+end
+
+def successful_response?(io) = Array(io.status).first.to_s.start_with?("2")
+
+def html?(io, content)
+  HTML_CONTENT_TYPES.include?(io.content_type) ||
+    HTML_SIGNATURE.match?(content.byteslice(0, 1024).b)
+end
+
 def unpack_bzip2(archive)
   execute "bzip2", "-d", archive
 end
diff --git a/test.rb b/test.rb
index 7654564..d3c74e3 100755
--- a/test.rb
+++ b/test.rb
@@ -22,6 +22,11 @@ def assert_qemu_system(architecture, firmwares:)
   assert validator.valid?, validator.message
 end
 
+def assert_usable_firmwares(architecture)
+  validator = FirmwareValidator.new(architecture)
+  assert validator.valid?, validator.message
+end
+
 def assert_only_system_dependencies(architecture)
   return unless QemuSystemValidator.host_os == "macos"
 
@@ -62,6 +67,10 @@ def assert_statically_linked(architecture)
         ]
       end
 
+      it "contains usable firmware files for x86_64" do
+        assert_usable_firmwares "x86_64"
+      end
+
       it "is only linked with system dependencies" do
         assert_only_system_dependencies "x86_64"
       end
@@ -77,10 +86,13 @@ def assert_statically_linked(architecture)
           efi-e1000.rom
           efi-virtio.rom
           uefi.fd
-          linaro_uefi.fd
         ]
       end
 
+      it "contains usable firmware files for arm64" do
+        assert_usable_firmwares "aarch64"
+      end
+
       it "is only linked with system dependencies" do
         assert_only_system_dependencies "aarch64"
       end
@@ -99,6 +111,10 @@ def assert_statically_linked(architecture)
         ]
       end
 
+      it "contains usable firmware files for riscv64" do
+        assert_usable_firmwares "riscv64"
+      end
+
       it "is only linked with system dependencies" do
         assert_only_system_dependencies "riscv64"
       end
@@ -200,6 +216,24 @@ def firmware_paths
       @firmware_paths ||= paths.filter { _1.start_with?(firmware_directory) }
     end
 
+    # The contents have to be read while the archive is being iterated, an
+    # entry cannot be read after the reader has moved past it.
+    def firmware_files
+      @firmware_files ||= File.open(filename) do |io|
+        firmware_files = []
+
+        Gem::Package::TarReader.new(io) do |tar|
+          tar.each do |entry|
+            next unless firmware?(entry)
+
+            firmware_files << Firmware.new(basename(entry), entry.read.to_s)
+          end
+        end
+
+        firmware_files
+      end
+    end
+
     def qemu_binary
       @qemu_binary ||= paths.filter { _1.start_with?("bin/qemu") }
     end
@@ -211,6 +245,16 @@ def firmwares
     def firmware_directory
       "share/qemu/"
     end
+
+    private
+
+    def firmware?(entry)
+      entry.file? && full_name(entry).start_with?(firmware_directory)
+    end
+
+    def basename(entry) = full_name(entry).delete_prefix(firmware_directory)
+
+    def full_name(entry) = entry.full_name.delete_prefix("./")
   end
 
   class MessageFormatter
@@ -266,3 +310,70 @@ def to_full_path(array)
     end
   end
 end
+
+# Verifies that the bundled firmware files actually contain firmware. A failed
+# download can produce an HTML error or landing page, which is otherwise
+# indistinguishable from a correct bundle since the file is still present.
+class FirmwareValidator
+  def initialize(architecture)
+    @architecture = architecture
+  end
+
+  def valid? = unusable_firmwares.empty?
+
+  def message
+    ["Unusable firmware files in '#{tar_file.filename}':"]
+      .concat(unusable_firmwares.map(&:message))
+      .join("\n")
+  end
+
+  private
+
+  attr_reader :architecture
+
+  def unusable_firmwares
+    @unusable_firmwares ||= tar_file.firmware_files.reject(&:usable?)
+  end
+
+  def tar_file
+    @tar_file ||= QemuSystemValidator::TarFile.for(
+      architecture: architecture,
+      host_os: QemuSystemValidator.host_os
+    )
+  end
+end
+
+# A single firmware file extracted from a bundle.
+class Firmware
+  # The smallest firmware bundled, kvmvapic.bin, is a few kilobytes.
+  MINIMUM_SIZE = 4096
+
+  private_constant :MINIMUM_SIZE
+
+  HTML_SIGNATURE = /\A\s*<(?:!doctype\s+html|html[\s>])/i
+
+  private_constant :HTML_SIGNATURE
+
+  attr_reader :name
+
+  def initialize(name, content)
+    @name = name
+    @content = content
+  end
+
+  def usable? = !html? && large_enough?
+
+  def message
+    return "'#{name}' is an HTML document, not firmware" if html?
+
+    "'#{name}' is #{content.bytesize} bytes, expected at least #{MINIMUM_SIZE}"
+  end
+
+  private
+
+  attr_reader :content
+
+  def html? = HTML_SIGNATURE.match?(content.byteslice(0, 1024).b)
+
+  def large_enough? = content.bytesize >= MINIMUM_SIZE
+end