diff --git a/ChangeLog b/ChangeLog
index 00d1a3a14f..1c364af085 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+Sun Aug 30 10:24:43 2009  Tanaka Akira  <akr@fsij.org>
+
+	* time.c (eq): apply RTEST.
+	  (ne): ditto.
+	  (add): avoid method dispatch for bignums.
+	  (sub): ditto.
+	  (mul): ditto.
+	  (mod): ditto.
+
 Sun Aug 30 09:45:11 2009  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (bigmul1_single): new function specialized respect to
diff --git a/time.c b/time.c
index e67a7bc5f7..bc2e769491 100644
--- a/time.c
+++ b/time.c
@@ -106,17 +106,51 @@ rb_localtime(const time_t *tm, struct tm *result)
 static ID id_divmod, id_mul, id_submicro, id_subnano;
 static ID id_eq, id_ne, id_quo, id_div, id_cmp, id_lshift;
 
-#define eq(x,y) (rb_funcall((x), id_eq, 1, (y)))
-#define ne(x,y) (rb_funcall((x), id_ne, 1, (y)))
+#define eq(x,y) (RTEST(rb_funcall((x), id_eq, 1, (y))))
+#define ne(x,y) (RTEST(rb_funcall((x), id_ne, 1, (y))))
 #define lt(x,y) (RTEST(rb_funcall((x), '<', 1, (y))))
 #define gt(x,y) (RTEST(rb_funcall((x), '>', 1, (y))))
 #define le(x,y) (!gt(x,y))
 #define ge(x,y) (!lt(x,y))
-#define add(x,y) (rb_funcall((x), '+', 1, (y)))
-#define sub(x,y) (rb_funcall((x), '-', 1, (y)))
-#define mul(x,y) (rb_funcall((x), '*', 1, (y)))
+
+static VALUE
+add(VALUE x, VALUE y)
+{
+    switch (TYPE(x)) {
+      case T_BIGNUM: return rb_big_plus(x, y);
+      default: return rb_funcall(x, '+', 1, y);
+    }
+}
+
+static VALUE
+sub(VALUE x, VALUE y)
+{
+    switch (TYPE(x)) {
+      case T_BIGNUM: return rb_big_minus(x, y);
+      default: return rb_funcall(x, '-', 1, y);
+    }
+}
+
+static VALUE
+mul(VALUE x, VALUE y)
+{
+    switch (TYPE(x)) {
+      case T_BIGNUM: return rb_big_mul(x, y);
+      default: return rb_funcall(x, '*', 1, y);
+    }
+}
+
 #define div(x,y) (rb_funcall((x), id_div, 1, (y)))
-#define mod(x,y) (rb_funcall((x), '%', 1, (y)))
+
+static VALUE
+mod(VALUE x, VALUE y)
+{
+    switch (TYPE(x)) {
+      case T_BIGNUM: return rb_big_modulo(x, y);
+      default: return rb_funcall(x, '%', 1, y);
+    }
+}
+
 #define neg(x) (sub(INT2FIX(0), (x)))
 #define cmp(x,y) (rb_funcall((x), id_cmp, 1, (y)))
 #define lshift(x,y) (rb_funcall((x), id_lshift, 1, (y)))