diff --git a/Libraries/LibJS/CMakeLists.txt b/Libraries/LibJS/CMakeLists.txt
index fa662b37338..11ff2360236 100644
--- a/Libraries/LibJS/CMakeLists.txt
+++ b/Libraries/LibJS/CMakeLists.txt
@@ -275,8 +275,14 @@ if("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "i.86.*")
     target_link_libraries(LibJS PRIVATE atomic)
 endif()
 
-# This flag has no effect on Windows
-if (NOT WIN32)
+if (WIN32)
+    # FIXME: Windows on ARM
+    target_link_libraries(LibJS PRIVATE clang_rt.builtins-x86_64.lib)
+    # FIXME: This is a hack to get around lld-link error undefined symbol GC::HeapBlockBase::block_size
+    #        LibGC HeapBlock.obj is given directly to LibJS linker
+    target_link_libraries(LibJS PRIVATE $<FILTER:$<TARGET_OBJECTS:LibGC>,INCLUDE,HeapBlock>)
+else()
+    # This flag has no effect on Windows
     target_compile_options(LibJS PRIVATE -fno-omit-frame-pointer)
 endif()
 
diff --git a/Libraries/LibJS/Contrib/Test262/AgentObject.cpp b/Libraries/LibJS/Contrib/Test262/AgentObject.cpp
index 57fd43c16ac..3f34714b072 100644
--- a/Libraries/LibJS/Contrib/Test262/AgentObject.cpp
+++ b/Libraries/LibJS/Contrib/Test262/AgentObject.cpp
@@ -5,10 +5,10 @@
  */
 
 #include <AK/Time.h>
+#include <LibCore/System.h>
 #include <LibJS/Contrib/Test262/AgentObject.h>
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/Object.h>
-#include <unistd.h>
 
 namespace JS::Test262 {
 
@@ -41,7 +41,7 @@ JS_DEFINE_NATIVE_FUNCTION(AgentObject::monotonic_now)
 JS_DEFINE_NATIVE_FUNCTION(AgentObject::sleep)
 {
     auto milliseconds = TRY(vm.argument(0).to_i32(vm));
-    ::usleep(milliseconds * 1000);
+    (void)Core::System::sleep_ms(milliseconds);
     return js_undefined();
 }