diff --git a/Libraries/LibCore/File.cpp b/Libraries/LibCore/File.cpp
index 27f36fdd4018..a2f26cf7eb05 100644
--- a/Libraries/LibCore/File.cpp
+++ b/Libraries/LibCore/File.cpp
@@ -7,15 +7,11 @@
 
 #include <LibCore/File.h>
 #include <LibCore/System.h>
-#include <fcntl.h>
 
 #if !defined(AK_OS_WINDOWS)
 #    include <unistd.h>
 #else
-#    include <WinSock2.h>
-#    define STDIN_FILENO _fileno(stdin)
-#    define STDOUT_FILENO _fileno(stdout)
-#    define STDERR_FILENO _fileno(stderr)
+#    include <AK/Windows.h>
 #endif
 
 namespace Core {
diff --git a/Libraries/LibCore/System.h b/Libraries/LibCore/System.h
index 323982dd880a..c68f21b95c10 100644
--- a/Libraries/LibCore/System.h
+++ b/Libraries/LibCore/System.h
@@ -33,7 +33,11 @@
 #    include <utime.h>
 #else
 #    include "SocketAddressWindows.h"
+#    include <io.h>
 #    define O_CLOEXEC O_NOINHERIT
+#    define STDIN_FILENO _get_osfhandle(_fileno(stdin))
+#    define STDOUT_FILENO _get_osfhandle(_fileno(stdout))
+#    define STDERR_FILENO _get_osfhandle(_fileno(stderr))
 #    define S_ISDIR(mode) (((mode) & S_IFMT) == S_IFDIR)
 #    define S_ISREG(mode) (((mode) & S_IFMT) == S_IFREG)
 using sighandler_t = void (*)(int);
diff --git a/Libraries/LibCore/SystemWindows.cpp b/Libraries/LibCore/SystemWindows.cpp
index fec598601ef4..9194af4a8d7a 100644
--- a/Libraries/LibCore/SystemWindows.cpp
+++ b/Libraries/LibCore/SystemWindows.cpp
@@ -263,4 +263,9 @@ u64 physical_memory_bytes()
     return ms.ullTotalPhys;
 }
 
+ErrorOr<bool> isatty(int handle)
+{
+    return GetFileType(to_handle(handle)) == FILE_TYPE_CHAR;
+}
+
 }
diff --git a/UI/Headless/Fixture.cpp b/UI/Headless/Fixture.cpp
index d17281e599b1..9254e6c80109 100644
--- a/UI/Headless/Fixture.cpp
+++ b/UI/Headless/Fixture.cpp
@@ -47,6 +47,9 @@ class HttpEchoServerFixture final : public Fixture {
 
 ErrorOr<void> HttpEchoServerFixture::setup(WebView::WebContentOptions& web_content_options)
 {
+#ifdef AK_OS_WINDOWS
+    VERIFY(0 && "Ladybird::HttpEchoServerFixture::setup is not implemented");
+#else
     auto const script_path = LexicalPath::join(s_fixtures_path, m_script_path);
     auto const arguments = Vector { script_path.string(), "--directory", Ladybird::Application::the().test_root_path };
 
@@ -81,10 +84,14 @@ ErrorOr<void> HttpEchoServerFixture::setup(WebView::WebContentOptions& web_conte
         warnln("Failed to read echo server port from buffer: '{}'", raw_output);
 
     return {};
+#endif
 }
 
 void HttpEchoServerFixture::teardown_impl()
 {
+#ifdef AK_OS_WINDOWS
+    VERIFY(0 && "Ladybird::HttpEchoServerFixture::teardown_impl is not implemented");
+#else
     VERIFY(m_process.has_value());
 
     auto script_path = LexicalPath::join(s_fixtures_path, m_script_path);
@@ -98,6 +105,7 @@ void HttpEchoServerFixture::teardown_impl()
     }
 
     m_process = {};
+#endif
 }
 
 void Fixture::initialize_fixtures()
diff --git a/UI/Headless/Test.cpp b/UI/Headless/Test.cpp
index 50ce346d5d0d..e82381696362 100644
--- a/UI/Headless/Test.cpp
+++ b/UI/Headless/Test.cpp
@@ -182,7 +182,7 @@ void run_dump_test(HeadlessWebView& view, Test& test, URL::URL const& url, int t
             return TestResult::Pass;
         }
 
-        auto const color_output = isatty(STDOUT_FILENO) ? Diff::ColorOutput::Yes : Diff::ColorOutput::No;
+        auto const color_output = TRY(Core::System::isatty(STDOUT_FILENO)) ? Diff::ColorOutput::Yes : Diff::ColorOutput::No;
 
         if (color_output == Diff::ColorOutput::Yes)
             outln("\n\033[33;1mTest failed\033[0m: {}", url);
@@ -531,7 +531,7 @@ ErrorOr<void> run_tests(Core::AnonymousBuffer const& theme, Web::DevicePixelSize
     bool all_tests_ok = true;
 
     // Keep clearing and reusing the same line if stdout is a TTY.
-    bool log_on_one_line = app.verbosity < Application::VERBOSITY_LEVEL_LOG_TEST_DURATION && isatty(STDOUT_FILENO) == 1;
+    bool log_on_one_line = app.verbosity < Application::VERBOSITY_LEVEL_LOG_TEST_DURATION && TRY(Core::System::isatty(STDOUT_FILENO));
     outln("Running {} tests...", tests.size());
 
     auto all_tests_complete = Core::Promise<Empty>::construct();
diff --git a/UI/Headless/main.cpp b/UI/Headless/main.cpp
index 158d659e8af2..0057787f0a12 100644
--- a/UI/Headless/main.cpp
+++ b/UI/Headless/main.cpp
@@ -61,6 +61,8 @@ static ErrorOr<NonnullRefPtr<Core::Timer>> load_page_for_screenshot_and_exit(Cor
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
+    AK::set_rich_debug_enabled(true);
+
     WebView::platform_init();
 
     auto app = Ladybird::Application::create(arguments, "about:newtab"sv);