diff --git a/ChangeLog b/ChangeLog
index a4bb4ecf1d..f6bec84f5b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon May 11 08:37:04 2009  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* ext/bigdecimal/bigdecimal.c (BigDecimal_coerce): support
+	   coercing into Rational.   [ruby-core:23415]
+
 Mon May 11 04:39:45 2009  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* lib/net/smtp.rb (Net::SMTP#check_auth_args): should not change
diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c
index 0abc00ab61..2f4b9ada34 100644
--- a/ext/bigdecimal/bigdecimal.c
+++ b/ext/bigdecimal/bigdecimal.c
@@ -675,11 +675,16 @@ BigDecimal_coerce(VALUE self, VALUE other)
     ENTER(2);
     VALUE obj;
     Real *b;
-    if(TYPE(other) == T_FLOAT) {
-       obj = rb_assoc_new(other, BigDecimal_to_f(self));
-    } else {
-       GUARD_OBJ(b,GetVpValue(other,1));
-       obj = rb_assoc_new(b->obj, self);
+    switch (TYPE(other)) {
+      case T_FLOAT:
+	obj = rb_assoc_new(other, BigDecimal_to_f(self));
+	break;
+      case T_RATIONAL:
+	obj = rb_assoc_new(other, BigDecimal_to_r(self));
+	break;
+      default:
+	GUARD_OBJ(b,GetVpValue(other,1));
+	obj = rb_assoc_new(b->obj, self);
     }
     return obj;
 }