diff --git a/ChangeLog b/ChangeLog
index 6216982312..4bb04c1b03 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Thu Dec  1 07:03:51 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* configure.in: add sys/prctl.h test.
+	* thread_pthread.c (thread_timer): call prctl(PR_SET_NAME) to change
+	  thread name. It may help to debug.
+
 Wed Nov 30 23:35:45 2011  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* variable.c (rb_path2class): don't raise NameError when the middle
diff --git a/configure.in b/configure.in
index b17c280735..e37849eadc 100644
--- a/configure.in
+++ b/configure.in
@@ -1128,7 +1128,7 @@ AC_CHECK_HEADERS(limits.h sys/file.h sys/ioctl.h sys/syscall.h\
 		 syscall.h pwd.h grp.h a.out.h utime.h direct.h sys/resource.h \
 		 sys/mkdev.h sys/utime.h xti.h netinet/in_systm.h float.h ieeefp.h \
 		 ucontext.h intrinsics.h langinfo.h locale.h sys/sendfile.h time.h \
-		 net/socket.h sys/socket.h process.h)
+		 net/socket.h sys/socket.h process.h sys/prctl.h)
 
 AC_TYPE_SIZE_T
 RUBY_CHECK_SIZEOF(size_t, [int long void*], [], [@%:@include <sys/types.h>])
diff --git a/thread_pthread.c b/thread_pthread.c
index 5e76e65d6d..0da4aee67f 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -24,6 +24,9 @@
 #elif HAVE_SYS_FCNTL_H
 #include <sys/fcntl.h>
 #endif
+#if HAVE_SYS_PRCTL_H
+#include <sys/prctl.h>
+#endif
 
 static void native_mutex_lock(pthread_mutex_t *lock);
 static void native_mutex_unlock(pthread_mutex_t *lock);
@@ -1127,6 +1130,10 @@ thread_timer(void *p)
 
     if (TT_DEBUG) WRITE_CONST(2, "start timer thread\n");
 
+#ifdef __linux__
+    prctl(PR_SET_NAME, "ruby-timer-thr");
+#endif
+
     while (system_working > 0) {
 	fd_set rfds;
 	int need_polling;