diff --git a/runtime/vm/os_thread.cc b/runtime/vm/os_thread.cc
index a3d8b32cdc3..d190c80eff7 100644
--- a/runtime/vm/os_thread.cc
+++ b/runtime/vm/os_thread.cc
@@ -20,9 +20,7 @@ OSThread* OSThread::thread_list_head_ = NULL;
 Mutex* OSThread::thread_list_lock_ = NULL;
 bool OSThread::creation_enabled_ = false;
 
-#if defined(HAS_C11_THREAD_LOCAL)
 thread_local ThreadState* OSThread::current_vm_thread_ = NULL;
-#endif
 
 OSThread::OSThread()
     : BaseThread(true),
@@ -282,14 +280,12 @@ void OSThread::SetCurrentTLS(BaseThread* value) {
   // Provides thread-local destructors.
   SetThreadLocal(thread_key_, reinterpret_cast<uword>(value));
 
-#if defined(HAS_C11_THREAD_LOCAL)
   // Allows the C compiler more freedom to optimize.
   if ((value != NULL) && !value->is_os_thread()) {
     current_vm_thread_ = static_cast<Thread*>(value);
   } else {
     current_vm_thread_ = NULL;
   }
-#endif
 }
 
 OSThreadIterator::OSThreadIterator() {
diff --git a/runtime/vm/os_thread.h b/runtime/vm/os_thread.h
index 7601cdcc4d3..b1019e870ce 100644
--- a/runtime/vm/os_thread.h
+++ b/runtime/vm/os_thread.h
@@ -12,11 +12,6 @@
 #include "vm/allocation.h"
 #include "vm/globals.h"
 
-// On iOS, thread_local requires iOS 9+.
-#if !DART_HOST_OS_IOS
-#define HAS_C11_THREAD_LOCAL 1
-#endif
-
 // Declare the OS-specific types ahead of defining the generic classes.
 #if defined(DART_HOST_OS_ANDROID)
 #include "vm/os_thread_android.h"
@@ -182,9 +177,7 @@ class OSThread : public BaseThread {
   }
   static void SetCurrent(OSThread* current) { SetCurrentTLS(current); }
 
-#if defined(HAS_C11_THREAD_LOCAL)
   static ThreadState* CurrentVMThread() { return current_vm_thread_; }
-#endif
 
   // TODO(5411455): Use flag to override default value and Validate the
   // stack size by querying OS.
@@ -308,9 +301,7 @@ class OSThread : public BaseThread {
   static OSThread* thread_list_head_;
   static bool creation_enabled_;
 
-#if defined(HAS_C11_THREAD_LOCAL)
   static thread_local ThreadState* current_vm_thread_;
-#endif
 
   friend class IsolateGroup;  // to access set_thread(Thread*).
   friend class OSThreadIterator;
diff --git a/runtime/vm/thread.h b/runtime/vm/thread.h
index d5f56ee1846..4277ee7610e 100644
--- a/runtime/vm/thread.h
+++ b/runtime/vm/thread.h
@@ -282,15 +282,7 @@ class Thread : public ThreadState {
 
   // The currently executing thread, or NULL if not yet initialized.
   static Thread* Current() {
-#if defined(HAS_C11_THREAD_LOCAL)
     return static_cast<Thread*>(OSThread::CurrentVMThread());
-#else
-    BaseThread* thread = OSThread::GetCurrentTLS();
-    if (thread == NULL || thread->is_os_thread()) {
-      return NULL;
-    }
-    return static_cast<Thread*>(thread);
-#endif
   }
 
   // Makes the current thread enter 'isolate'.
diff --git a/runtime/vm/thread_state.h b/runtime/vm/thread_state.h
index 58e57aae94a..e83bc26f4d7 100644
--- a/runtime/vm/thread_state.h
+++ b/runtime/vm/thread_state.h
@@ -25,15 +25,7 @@ class ThreadState : public BaseThread {
  public:
   // The currently executing thread, or NULL if not yet initialized.
   static ThreadState* Current() {
-#if defined(HAS_C11_THREAD_LOCAL)
     return OSThread::CurrentVMThread();
-#else
-    BaseThread* thread = OSThread::GetCurrentTLS();
-    if (thread == NULL || thread->is_os_thread()) {
-      return NULL;
-    }
-    return static_cast<ThreadState*>(thread);
-#endif
   }
 
   explicit ThreadState(bool is_os_thread);