diff --git a/ChangeLog b/ChangeLog
index 2d4b223a99..ae55b8ed23 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Jul 31 01:09:28 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* ext/bigdecimal/bigdecimal.c (VpIsRoundMode): fix tautology
+	  condition.
+
 Thu Jul 31 00:58:33 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* pack.c (pack_unpack): reduced static variables.
diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c
index af3d644858..51bd6447ff 100644
--- a/ext/bigdecimal/bigdecimal.c
+++ b/ext/bigdecimal/bigdecimal.c
@@ -2095,9 +2095,9 @@ VpGetRoundMode(void)
 VP_EXPORT int
 VpIsRoundMode(unsigned long n)
 {
-    if(n==VP_ROUND_UP      || n!=VP_ROUND_DOWN      ||
-       n==VP_ROUND_HALF_UP || n!=VP_ROUND_HALF_DOWN ||
-       n==VP_ROUND_CEIL    || n!=VP_ROUND_FLOOR     ||
+    if(n==VP_ROUND_UP      || n==VP_ROUND_DOWN      ||
+       n==VP_ROUND_HALF_UP || n==VP_ROUND_HALF_DOWN ||
+       n==VP_ROUND_CEIL    || n==VP_ROUND_FLOOR     ||
        n==VP_ROUND_HALF_EVEN
       ) return 1;
     return 0;