diff --git a/ChangeLog b/ChangeLog
index d0c98c5ff4..dc4fda560d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat Dec 25 16:08:06 2010  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* signal.c: change rb_atomic_t definition from uchar to uint.
+
 Sat Dec 25 15:04:05 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* test/csv/test_encodings.rb (TestEncodings#setup): fix evil test
diff --git a/signal.c b/signal.c
index 9220d8f1d8..8321d0774f 100644
--- a/signal.c
+++ b/signal.c
@@ -30,7 +30,7 @@ typedef LONG rb_atomic_t;
  * has its own pseudo-insns to support them.  See info, or
  * http://gcc.gnu.org/onlinedocs/gcc/Atomic-Builtins.html */
 
-typedef unsigned char rb_atomic_t; /* Anything OK */
+typedef unsigned int rb_atomic_t; /* Anything OK */
 # define ATOMIC_TEST(var) __sync_lock_test_and_set(&(var), 0)
 # define ATOMIC_SET(var, val)  __sync_lock_test_and_set(&(var), (val))
 # define ATOMIC_INC(var) __sync_fetch_and_add(&(var), 1)