diff --git a/boehm-gc/ChangeLog b/boehm-gc/ChangeLog
index ed6ee543650..d2a80cc1fcb 100644
--- a/boehm-gc/ChangeLog
+++ b/boehm-gc/ChangeLog
@@ -1,3 +1,7 @@
+2009-05-17  Dave Korn  <dave.korn.cygwin@gmail.com>
+
+	* win32_threads.c (GC_get_thread_stack_base):  Implement for Cygwin.
+
 2009-03-01  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
 	* configure: Regenerate.
diff --git a/boehm-gc/win32_threads.c b/boehm-gc/win32_threads.c
index ba53d86fbd1..ffb34e0a8b1 100644
--- a/boehm-gc/win32_threads.c
+++ b/boehm-gc/win32_threads.c
@@ -753,6 +753,12 @@ int GC_pthread_detach(pthread_t thread)
     return result;
 }
 
+GC_PTR GC_get_thread_stack_base()
+{
+  extern GC_PTR _tlsbase __asm__ ("%fs:4");
+  return _tlsbase;
+}
+
 #else /* !CYGWIN32 */
 
 /*