diff --git a/ChangeLog b/ChangeLog
index 44cea7dcae..4064bb6832 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Jul 12 21:38:02 2007  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* insns.def (opt_succ): use LONG_MAX as maximum Fixnum VALUE.
+
 Thu Jul 12 18:42:18 2007  Tanaka Akira  <akr@fsij.org>
 
 	* range.c (range_max): use FIX2LONG instead of FIX2INT to avoid
diff --git a/insns.def b/insns.def
index 9fc4fcc9d4..b22b76323a 100644
--- a/insns.def
+++ b/insns.def
@@ -2304,8 +2304,7 @@ opt_succ
 	    const VALUE obj = INT2FIX(1);
 	    /* fixnum + INT2FIX(1) */
 	    val = (recv + (obj & (~1)));
-	    if ((~(recv ^ obj) & (recv ^ val)) &
-		((VALUE)0x01 << ((sizeof(VALUE) * CHAR_BIT) - 1))) {
+	    if ((~(recv ^ obj) & (recv ^ val)) & (LONG_MAX + 1)) {
 		val = rb_big_plus(rb_int2big(FIX2LONG(recv)),
 				  rb_int2big(FIX2LONG(obj)));
 	    }