diff --git a/ChangeLog b/ChangeLog
index 2d1ae18b46..478a0b49c3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Thu Feb  4 09:55:38 2010  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* configure.in: FreeBSD, DragonFly BSD and Mac OS X needs
+	  pthread_np.h to use pthread_*_np functions.
+	  Mac OS X's pthread_*_np also depend sys/signal.h,
+	  but it is included at signal.h via vm_core.h via thread.c.
+
 Thu Feb  4 08:15:53 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* lib/delegate.rb (Delegator): now inherits BasicObject.
diff --git a/configure.in b/configure.in
index 69b8b7170a..3a79b7b5a0 100644
--- a/configure.in
+++ b/configure.in
@@ -1499,6 +1499,7 @@ if test x"$enable_pthread" = xyes; then
 	AC_DEFINE(_REENTRANT)
 	AC_DEFINE(_THREAD_SAFE)
 	AC_DEFINE(HAVE_LIBPTHREAD)
+	AC_CHECK_HEADERS(pthread_np.h)
 	AS_CASE([$pthread_lib],
 	[c],    [],
 	[root], [],