diff --git a/ChangeLog b/ChangeLog
index d09528a453..ad5f1ca1ce 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Sat Jun 11 19:27:06 2011  Hiroshi Nakamura  <nahi@ruby-lang.org>
+
+	* ext/openssl/ossl_x509req.c: raise RequestError instead of
+	  CertificateError when Request#to_der gets an error from OpenSSL.
+	  Patch from Ippei Obayashi, see #4420. I cannot write a test for
+	  this... Request does not allow to create broken bytes...
+
 Sat Jun 11 19:34:51 2011  Tadayoshi Funaba  <tadf@dotrb.org>
 
 	* ext/date/date_core.c (Date::(ABBR_)?(MONTH|DAY)NAMES): should be usascii.
diff --git a/ext/openssl/ossl_x509req.c b/ext/openssl/ossl_x509req.c
index f68d215da5..ec5b4a34e8 100644
--- a/ext/openssl/ossl_x509req.c
+++ b/ext/openssl/ossl_x509req.c
@@ -171,7 +171,7 @@ ossl_x509req_to_der(VALUE self)
 
     GetX509Req(self, req);
     if ((len = i2d_X509_REQ(req, NULL)) <= 0)
-	ossl_raise(eX509CertError, NULL);
+	ossl_raise(eX509ReqError, NULL);
     str = rb_str_new(0, len);
     p = (unsigned char *)RSTRING_PTR(str);
     if (i2d_X509_REQ(req, &p) <= 0)