diff --git a/ChangeLog b/ChangeLog
index 5cc81e6e11..78e0449543 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Thu Jul 24 16:05:22 2003  Nobuyoshi Nakada  <nobu.nokada@softhome.net>
+
+	* configure.in (AC_C_VOLATILE): check if volatile works.
+
+	* defines.h (volatile): removed.
+
+	* eval.c (rb_thread_group): Thread#group.  [new]
+
 Thu Jul 24 15:50:42 JST 2003  GOTOU Yuuzou  <gotoyuzo@notwork.org>
 
 	* ext/openssl/extconf.rb: add check for win32 OpenSSL libraries.
diff --git a/configure.in b/configure.in
index 96fabbf96d..ea0a466111 100644
--- a/configure.in
+++ b/configure.in
@@ -475,6 +475,7 @@ AC_C_BIGENDIAN
 AC_C_CONST
 AC_C_CHAR_UNSIGNED
 AC_C_INLINE
+AC_C_VOLATILE
 
 AC_CACHE_CHECK(whether right shift preserve sign bit, rb_cv_rshift_sign,
     [AC_TRY_RUN([
diff --git a/defines.h b/defines.h
index 59b348a2cc..6fd17808ae 100644
--- a/defines.h
+++ b/defines.h
@@ -12,10 +12,6 @@
 
 #define RUBY
 
-#if !defined(__STDC__) && !defined(_MSC_VER)
-# define volatile
-#endif
-
 #ifdef __cplusplus
 # ifndef  HAVE_PROTOTYPES
 #  define HAVE_PROTOTYPES 1
diff --git a/eval.c b/eval.c
index 13f9bec54a..ed3815ba6f 100644
--- a/eval.c
+++ b/eval.c
@@ -9178,6 +9178,17 @@ rb_thread_abort_exc_set(thread, val)
     return val;
 }
 
+VALUE
+rb_thread_group(thread)
+    VALUE thread;
+{
+    VALUE group = rb_thread_check(thread)->thgroup;
+    if (!group) {
+	group = Qnil;
+    }
+    return group;
+}
+
 #define THREAD_ALLOC(th) do {\
     th = ALLOC(struct thread);\
 \
@@ -10024,6 +10035,7 @@ Init_Thread()
     rb_define_method(rb_cThread, "priority", rb_thread_priority, 0);
     rb_define_method(rb_cThread, "priority=", rb_thread_priority_set, 1);
     rb_define_method(rb_cThread, "safe_level", rb_thread_safe_level, 0);
+    rb_define_method(rb_cThread, "group", rb_thread_group, 0);
 
     rb_define_method(rb_cThread, "[]", rb_thread_aref, 1);
     rb_define_method(rb_cThread, "[]=", rb_thread_aset, 2);