diff --git a/compiler-rt/lib/asan/asan_thread.cc b/compiler-rt/lib/asan/asan_thread.cc
index 5c2289491535..16648fe7485a 100644
--- a/compiler-rt/lib/asan/asan_thread.cc
+++ b/compiler-rt/lib/asan/asan_thread.cc
@@ -174,10 +174,10 @@ thread_return_t AsanThread::ThreadStart(uptr os_id) {
 }
 
 void AsanThread::SetThreadStackAndTls() {
-  uptr stack_size = 0, tls_size = 0;
-  GetThreadStackAndTls(tid() == 0, &stack_bottom_, &stack_size, &tls_begin_,
+  uptr tls_size = 0;
+  GetThreadStackAndTls(tid() == 0, &stack_bottom_, &stack_size_, &tls_begin_,
                        &tls_size);
-  stack_top_ = stack_bottom_ + stack_size;
+  stack_top_ = stack_bottom_ + stack_size_;
   tls_end_ = tls_begin_ + tls_size;
 
   int local;
diff --git a/compiler-rt/lib/asan/asan_thread.h b/compiler-rt/lib/asan/asan_thread.h
index 00a1233993a5..bd92cfe4c6dd 100644
--- a/compiler-rt/lib/asan/asan_thread.h
+++ b/compiler-rt/lib/asan/asan_thread.h
@@ -62,7 +62,7 @@ class AsanThread {
 
   uptr stack_top() { return stack_top_; }
   uptr stack_bottom() { return stack_bottom_; }
-  uptr stack_size() { return stack_top_ - stack_bottom_; }
+  uptr stack_size() { return stack_size_; }
   uptr tls_begin() { return tls_begin_; }
   uptr tls_end() { return tls_end_; }
   u32 tid() { return context_->tid; }
@@ -116,6 +116,9 @@ class AsanThread {
   void *arg_;
   uptr  stack_top_;
   uptr  stack_bottom_;
+  // stack_size_ == stack_top_ - stack_bottom_;
+  // It needs to be set in a async-signal-safe manner.
+  uptr  stack_size_;
   uptr tls_begin_;
   uptr tls_end_;