--- a/Source/WTF/wtf/Threading.cpp
+++ b/Source/WTF/wtf/Threading.cpp
@@ -130,9 +130,9 @@ static std::optional<size_t> NODELETE stackSize(ThreadType threadType)
 #endif
 }
 
-#if PLATFORM(COCOA) || OS(LINUX)
+#if PLATFORM(COCOA)
 // uid 1 is reserved for the main thread, assigned in Thread::initializeCurrentTLS
-// when current thread is detected as main thread. ++s_uid yields >= 2 for every non-main thread.
+// when pthread_main_np() returns true. ++s_uid yields >= 2 for every non-main thread.
 std::atomic<uint32_t> ThreadLike::s_uid { 1 };
 #else
 // On platforms without a way to detect the main thread before initializeMainThread()
--- a/Source/WTF/wtf/posix/ThreadingPOSIX.cpp
+++ b/Source/WTF/wtf/posix/ThreadingPOSIX.cpp
@@ -455,10 +455,8 @@ Thread& Thread::initializeCurrentTLS()
     // Not a WTF-created thread, Thread is not established yet.
     WTF::initialize();
 #if PLATFORM(COCOA)
     Ref thread = adoptRef(*new Thread(SchedulingPolicy::Other, pthread_main_np() ? IsMain::Yes : IsMain::No));
-#elif OS(LINUX)
-    Ref thread = adoptRef(*new Thread(SchedulingPolicy::Other, getpid() == static_cast<pid_t>(syscall(SYS_gettid)) ? IsMain::Yes : IsMain::No));
 #else
     Ref thread = adoptRef(*new Thread(SchedulingPolicy::Other));
 #endif